I got this book Read this if you want to take great photographs for Christmas. It has been pretty good until I got to this page that says NOT to use the 'M' mode. They recommend P, Av or Tv.

They equate shooting in 'P' mode to be similar to 'M' mode, but with M taking longer.

if I'm using artificial lighting (flash, strobes, etc) I'm always in Manual mode.

if I'm shooting sports, I might be in Aperture or Shutter mode depending upon the conditions and my objectives. Or I might be in manual mode but with auto ISO... which is a great option if you have a camera with great high ISO performace

you will eventually get to the point where the mode doesn't really matter for you because - in manual mode - you'll be able to estimate your correct combo of shutter and aperture (within a stop) 95% of the time

I shoot in the mode best suited for what I'm shooting.  Generally, I use aperture priority most, followed by shutter priority and manual.

I haven't had my DSLRs on "P" since I picked up a D70 back in 2004, other than to hand the camera to someone else if I need them to take a photo for me.  Rarely happens.

This is a IMHO and YMMV.

I'm in Av for about 99% of my shooting.  I dial the exposure comp a lot though.

Edit:  One if my bodies doesn't even have an "auto" setting. 

I do use P occasionally if I'm just taking family photos and I'm doing more socializing than being 'the photographer.'

Seems aperture mode is the post popular (by the number of comments made on it).

Why this vs others?

I'm probably in manual mode at least 90% of the time.  I'm a control freak, and like to know that I am making the decisions about the pictures I take, rather than letting the camera make those decisions for me.  Sometimes I want a little over/under exposure, and the easiest way for me to get that, is to use the manual mode.

But, sometimes we all need help.  I haven't shot any sports/action pictures for a long time now, but if I do, then I use the same approach as NoVaGator......that is, aperture or shutter priority, or manual mode with auto-ISO.   With action shots, it can be necessary to change the exposure settings rapidly and frequently, due to changing lighting conditions.  That can be difficult to do in the manual mode, and thus the use of these other modes.  Even in these modes, however, I am still making the decisions.  I prioritize what is important to me (aperture, shutter speed, ISO), and then let the camera choose the other settings.

That is the same reason people use aperture priority so much.  It's because the DOF is their number one priority.  For instance, if I'm on vacation snapping pictures like every other tourist, then the shutter speed may not be so important.  So I can set the aperture and ISO, and let the camera choose the correct shutter speed for the exposure.

I have been using M mode since I got my camera (end of December). However, I find I am playing around with the aperture and shutter way too much to get the right balance. I am unsure of when looking at scene, as to where I should start and get frustrated when things aren't quite working out.

There are lots of ways to skin a cat, but I am going to suggest that you start by thinking about proper exposure, and your priorities.  I'll use my vacation pictures as an example.

When I go to Las Vegas, I often walk around taking pictures.  Lets say it's a nice bright day, so in this case, my first priority is to set my camera to its base ISO, which is 200.   Shutter speed is not that critical, since I'm mostly taking pictures of architecture.  So  setting the aperture is my second priority.

Most lenses hit their sweet spot (are at their sharpest) 2-3 stops down from wide open.  That would be f/5.6 to f/8.0 for my 17-35 lens.  I know from experience that those apertures (at those focal lengths) will give me all the DOF I need for the type of pictures I am taking. So I set the aperture to say f/8. Lastly, I use the exposure meter in the camera to help me set the shutter speed, to achieve a proper exposure.  And since I'm an old guy who started photography back around 1970, I often do a "sunny 16" calculation in my head, to confirm my exposure settings.  Yes, I use the meter in the camera for information, but I set everything using the manual mode.  After the first shot or two, I usually check the "blinking highlights" and histogram to confirm my exposure is where I want it.  

Now, lets say I come across the waterfalls at the Mirage, and I want to use a slow shutter speed to get the flowing water look. Shutter speed has now become a higher priority than aperture.  This is when  I will set the shutter speed first, and then change the aperture to maintain the proper exposure. My priorities have changed, so my approach to getting the proper exposure has changed.  If I slow down the shutter speed 3 stops, then I need to close down the aperture 3 stops.

You don't change settings for the heck of it, you change them for a reason. And always keep thinking about proper exposure.  

Prioritize what you want out of a picture first.   If you want a fast shutter speed, then start there.  Once you decide on that shutter speed, then set your aperture and ISO to get the proper exposure.  Just take it one step at a time, and you will be fine.

+1 on what Keoka said.

control your variables (except for one) until you've got the hang of it

In manual mode, I'd start with ISO 400 and f/8, and then only adjust your shutter speed to get the exposure you want

do that for a week

once you've figured that out, go with ISO 400, Shutter speed 1/500 sec, and only adjust your aperture to get the exposure you want

ISO 400 and f/8 is very common setting. If you are doing portraits then you want want a much wider aperture to blur out the background for more pleasant bokeh. If I need a higher shutter speed I will go to M mode 1/500-1/1250, f/8 and Auto ISO

I'm a very new beginner at DSLR. I've put my camera in manual mode and left it there most of the time. I do cheat sometimes and switch to auto mode to see what the camera sets everything at to get me a clue of what is close in manual. I am able to get shots of my children playing sports when they are standing still but when the action starts I have to switch to auto mode to keep up.

I honestly forget there are other modes and run solid manual mode.  Then again, considering I plan on moving up to a pro body without those, it is a good thing to do. 

For most photographers, the depth of field is the more important artistic variable of the shot. Figure out how much of the scene you want in focus, then adjust the rest of the exposure variables to account for that.

The trick to using the semi-auto exposure modes is understanding what the camera's light meter is doing for you (or to you) under the given lighting conditions.

I spend most of my time in aperture-priority mode. I pick the aperture for the desired depth of field. The camera picks the shutter speed for the chosen aperture and ISO. (I always use manual ISO.) If I don't like the shutter speed, I adjust the ISO to get a shutter speed in the range I want. (That want being either fast enough to cover my shaky hands, or fast enough to freeze any motion blur from the subject.)

For outdoor sports, I am in aperture-priority mode. I pick the depth of field (shallow, usually f/2.8 or f/4) and boost the ISO to get a fast shutter speed I like.

The only time I use speed-priority is when I need a special shutter speed to get the effects I want. Normally this is a slower speed to get prop blur in planes and helos.

For indoor sports, I use manual exposure mode. This is because I don't want the camera trying to out-think me. The settings I pick for aperture, shutter speed, and ISO are either correct and don't need adjustments from the camera; or they are wrong on purpose and will be fixed in post processing.

The catch with manual exposure is that if you are always agreeing with the camera's meter and thus always zeroing your settings to the pick of the camera, you are wasting your time and effort by not using aperture-priority mode or speed-priority mode, since that is what you are doing by hand any way.

When in a semi-auto mode, if the camera's meter is repeatedly off by a constant amount (say always underexposing by 1 stop due to snow) you can just dial in some exposure compensation to "fix" the constant metering "error".

Basically this - although I confess I have never thought of M and auto-ISO, but as the new owner of a camera with GREAT high-ISO performance, I need to experiment. That seems like a very useful solution.

I tend to shoot a lot of kids sports, and for those Shutter Priority works well for freezing action, but for stills (free-throws and the like) I routinely switch over the Aperture priority.

Outside, I tend to be in full Manual mode quite a bit more.

-shooter

I have been shooting Pentax DSLR's for 5 years now.  They have a TAv setting that i like a lot.  You set shutter speed and aperture and the camera varies the ISO.

I also shoot a lot in manual mode as I still have some old Pentax glass that I use.  A lot of times I disable autofocus and use manual focus too.  Since I have been using manual focus for 45 years or more, it is not a big deal to me.   Plus on closer shots I get to set the area I Want in focus.  

My cameras include the K5, K5-IIs, K3 and the awesome K1.  The K1 is full frame and the first DSLR I have used that makes me forget about film.  Plus if I use Pixel Shift I get Raw images with 191 meg of data to play with.   This makes it a great landscape and still life camera.  Plus they have in body shake reduction.    

With the built in GPS it can also track stars for up to 5 minutes (depending upon the focal length of the lens) by moving the sensor to follow them.

Aperture almost exclusively, followed by Manual. Shutter priority after that and P never gets used at all.

Av lets me choose the depth of field I want and allows me to keep my lens in the optimum sharpness range of around f/8. Unless I'm shooting sports I'll select the desired aperture then whatever ISO I need to keep the shutter speed in the usable territory and adjust from there.

Three words:  Depth Of Field (or lack thereof).

Aperture let's you get all kinds of creative with bokeh, subject focus, drawing attention to something in the shot, etc.

Shutter is good for freezing or blurring motion, but aperture lends greater impact to shots, IMO.

Yup.  It's also why I run pure manual, so I can dick with both of them on the fly.  It's especially important in summer when I'm doing a lot of firearm stuff.  Might be taking a photo with a good DoF in one shot, then have to run wide open at 1/2000 in the next shot 30 seconds later.  So I usually just let auto ISO do what it needs to do, and set aperture and shutter.

And in relation to DOF issues...

Where do most people focus the camera when taking landscaping pics? I found a few places recommend just beyond the foreground.

Mostly manual, sometimes Aperture priority. The big thing you have to watch when shooting manual is making sure when conditions change that you change all of your settings to match. I was at an air museum taking pictures last week, mostly in a hangar so I had the aperture pretty wide and the shutter speed down to get the shots I wanted. I was going to leave and saw that outside they had a rare early Russian bomber on display so I took some quick shots without paying attention to my settings, the outcome was those couple shots were so overexposed that even with the raw images in LR I couldn't get them to a usable state. Moral of the story, check your damn settings

So, let me get this straight in numbers I know.

I have a 10-18 lens with it being set at 14mm. My aperture is set at f/12.

If I am taking a picture of lets say the ocean, I want to be about a third of the way (horizontal wise) into the picture.  How does this work with cameras that have 40/50/60 focal points?

Fair enough.

I made it a long time in life with a single focus point in AF, and then a decent amount of time with about 5. Having infinite options doesn't always help.

-shooter

What distance to focus at will depend on which parts of the image you want in focus.
Since you are at f/12, one might assume you want pretty much everything in focus, which will be easy with the 14mm lens. Focus at about 3 feet for the hyperfocal distance.

When dealing with these deep depth of fields, the precision of the focus distance does not need to be overly accurate. Pick an object about the right distance away, lock the focus at that distance, and recompose the scene. For landscapes and other static subjects, you are normally using only single-point focus.

See this depth of field calculator for fun with the numbers:
http://www.dofmaster.com/dofjs.html

What if my camera isn't listed?

Pick something with a similar sensor size and megapixel count.
Or, if you know the Circle of Confusion for your camera, you can pick that value at the bottom of the list.

+1 I use the center AF point a LOT. My camera has 9 and I can only think of one or two times where I could've benefited from another one.

Thanks.

I am gonna search for an app too.

I did not spend much time researching the apps at the time, but these are the two I have on my Android phone:
https://play.google.com/store/apps/details?id=com.cunningdogsoftware.dofcalculator
https://play.google.com/store/apps/details?id=in.zendroid.hyperfocal

Depending on the situation, but Av gets the most use. Mostly the same as M except your shutter is based off the light balance setting which you control and the light sensor so IMHO its smarter as it adjusts to the scene... They all have their merits.

I almost exclusively use M, primarily because I use Nikon lenses on a Sony mirrorless, so I control focus, shutter speed, and aperture manually as I shoot.

ISO is generally left at base, unless I need more sensitivity for a particular shot.  If I'm in rapidly changing light conditions, I set my upper and lower ISO range and let the camera decide.

I use aperture priority the majority of the time. But I will also adjust some camera settings such as the auto shutter speed to have the camera lean towards a higher shutter speed if i want to stop the motion of people, like at a party.

I also use the custom settings. I have one where i am in apeture priority and everything else is auto but i limit the iso so the camera can't raise it to where there will be a lot of noise.

I find the semi auto (aperture priority) modes more useful than manual but i control a lot of the other settings by setting up the camera to do what i want. Basically defining a set range for the shutter speed or iso.

I use manual but also aperture priority as well.

I'm in manual about 95% of the time. Ap the other 5%. I set my aperture for desired look, then I'll generally ride the shutter speed until I need to up (or drop) ISO.

M almost all the time.  Aperture Priority if M isn't working.  I don't think I've used any of the Auto settings on either of my bodies.
Back in the stoned age circa 1976, I used a Fujica ST605 and a Vivitar 50mm prime.  Auto wasn't an option.

I use manual with Auto ISO on my Nikons in low but variable light at plays and concerts.  I get the DOF I want by fixing the aperture, a shutter that is reasonable to stop the action (not fast motion, but some - maybe 1/100 - 1/200), and lowest ISO to make the shot and keep the noise down.

For my Nikon D7100, I use the P-mode when shooting outdoors daylight with the lowest ISO when shooting outdoors. IF and when I use a polarizer the bump the ISO up to 320. I try to use the lowest ISO to keep the noise down.

For nighttime, I use Av and fill-flash with the highet ISOs.

I've shot three different activities today in 4-5 different lighting situations, all in A, with custom white balance settings when possible.

Someone turning out the lights in the middle of a shot makes that not possible.

I think I have about 300 pictures to cull.

-shooter

Manual or AP.

But I do weird stuff with mine, the white balance is all wacky and the color saturation is adjusted differently than normal.

Probably about 80% aperture priority, 20% manual.  AP generally gets me the exposures I want, but oftentimes I need to switch to manual.  

I have no idea what the P mode does on my D810

Those Japanese engineers busted ass maximizing performance.  They're smarter than I am, so I run AUTO baby!

Sometimes for a particular artistic shot/whatever, I'll try one of the other modes, but usually AUTO works just fine!

Auto works decent but you can really start pulling some insanely good shots off once you get out of auto mode and even into some of the PASM modes.  
(P)rogram is you basically set your depth of field or shutter and the camera will run the rest.  Basically rotate the dial counterclockwise to freeze motion or blur the background.  Clockwise to blur motion or deeper depth of field.
(A)perture you set the aperture you want and the camera runs the rest
(S)hutter.  Same thing.  Pick your shutter speed and it does the rest.
(M)anual.  Pure manual unless you select auto ISO.  Honestly on my camera, I have it set to use the lowest ISO possible given whatever settings I have.  50/50 if I run it on auto-iso or manual, just depends what's going on.  Sports stuff, auto ISO is king.

Auto ISO is great for action stuff where lighting conditions can change in a heartbeat.  Like here, I was shooting into the sun for the first shot, then with it at my back a couple seconds later.  No way I'd be able to swap settings that fast, so I let the camera take care of it.

That said, I'm also putting a hellacious frame count on my camera when I go out, so I have lots of practice with it.  All in all, I was over 3000 frames this past weekend.

If you like "auto" mode, you will love "Programmed" mode. It starts off as "auto" but lets you adjust the exposure parameters to pick your desired shutter speed or aperture by letting you cycle through the equivalent exposures.