That's okay by me.
Another thing to keep in mind is the correct tool for the job. That $85.00 Hanita Varimill does great on steels, but it won't perform correctly in aluminum or other softer materials. Cutter selection is more than just sharpness and size. There is rake angle, Positive, Negative, Nuetral, Carbide, HSS, Cobalt, all sorts of things and that's not even covering coatings.
I am not by any means a one stop source for all things Right about machining. However, if some folks can learn from what I've done wrong...
*ETA*
While we're on the subject of cutters...
Drills
Know your chip! Watch to see you don't have an uneven chip load coming out of the hole. A drill chip that is consistantly coming out longer on one side means your drill point is ground incorrectly. You've got the chisel point oriented wrong, or the drill point is ground off center, or you may not have enough relief on the back rake of the point. The last one usually manifests itself by taking an abnormally high ammount of power to push the tool through the work. The chips look...corrugated, or rippled and come out in little pie slices and often have little holes in them. A drill chip in most metals should look like those little spiral noodles you get in a pasta salad.
Learn to sharpen your own drills! I'm such a hypocrite for telling people this, I could do it once upon a time but now I just usually make things that look like a nail
Chatter/harmonics
Your speed is too high, or your feed is too low. Either drop the spindle speed or increase the feed (spin slower or push harder) and see where the sound takes you.
Another possibility is your rigidity in either the tool, the work, or both sucks. Although often in cases of work rigidity being low its more of a *CRASH BANG THUMPATHUMPATHUMPA.....silence* sound than a chatter sound. Check your fixturing for anything loose and flapping around. Make sure you have the work supported and you aren't trying to cut something sticking out like a noodle (either tool or work). A thin cross section of the work piece will often casue trouble with this and honestly sometimes you just gotta go with it. But check to see if you can hold it better anyway. Put a jackscrew under it, clamp it further in the vise, do that turning job in two ops instead of one if possible and if you're having chatter problems.
Also, consider your depth of cut. If you're too shallow, you're just tickling at the work and aren't getting a good enough bite to really get physics working for you yet. The tool is deflecting because it can find no real purchase in the material.
Dull tools can and will chatter, but mostly they will have a deeper, growly, impacting sound as they are trying to bulldoze material now instead of trying to shear it off. Check your cutters. Depending on the material, the wear or damage may not be readily noticeable, use a loupe or run your fingernail over the cutting edge. The sense of feel is of immeasurable value for this and highly underestimated especially by many beginners. You can feel a chipped cutter face by starting behind the corner (or wherever you suspect the damage to be) and running your fingernail softly along the edge. It will feel smooth and uniform until you get to a built up area or a chipped face, you will feel this as it drags on your nail and causes it to catch ever so slightly. Look there with the loupe, if it's built up you can try to hone it away with a stone. If it's chipped, well you will have to get it sharpened or replaced if you are trying to maintain size. If you aren't, you can keep it and use it for a roughing tool.
Tight Enough Is Not Too Tight
When you put a chuck on the lathe, or load up a vise on the table for the love of God, do not use a three foot cheater bar!
Get a torque wrench if you have to, but overtightening causes damage, damage causes rigidity and/or accuracy problems, and those thigns cost money. One place I worked, we had a guy that used a cheater on everything. I was trying to set something up on the machine he normally ran and noticed I couldn't fit the "good" T-Nuts into the slots past the point where the G54 vise was usually mounted. Couldn't get to it from the other way either but they did fit in the slots not normally used for mounting vises.
Weird...
A little investigation showed that he had over tightened things so much and so often he had mushroomed out little spots in the T-Slots just enough that the taller ("good) T-Nuts couldn't get past those points. A quick indicator check showed that this had not translated into a raised area on the mill table...but damn.
Threads ripped out of vise solid jaws, ruined fixture plates, screws that have to be machined out of those plates, broken angle plates, distorted vises, etc.
All these things from people overtightening a simple capscrew. Don't be that guy.