What would YOU want in one?
I'm thinking beyond the store bought ones.
Things Id like to have would be super glue for cuts.
Suture kits
Epi pen
quick clot

The SF has the answers you seek.

Now with Linky!

shears or a small knife.

More specifics, bro.

While they contain the same general items, the kit I keep on my belt while running my chain saw is different than the kit I keep in my truck or in a go bag, for example.

Start with training.  Build a kit after that.

 

I recommend band-aids. Lots of them. Preferably of the Hello Kitty or Spongebob variety....and a bottle of Bulleit.

vodka

Remember that all that stuff expires and needs to be inspected semi-annually, at least.Sterile packaging that lasts forever in a climate controlled cabinet does not last in a soft bag that's subject to radical temperature changes.

gloves
4x4s
tape
quality stethoscope, not the freebie Chinese piece of junk that came with the:
sphygmomanometer (blood pressure cuff)
timepiece with second hand
trauma dressings
sterile normal saline
water sterilization tablets
water containers
burn sheet
mylar emergency blankets
cravats
occlusive dressing if you don't want to learn how to improvise one from the wrapper of the trauma dressing you were using, anyway.
quality shears

PEN AND PAPER - this is the most important thing you can have. What you want to do is observe changes in pulse, respiration, and blood pressure. You need to write down what you measured and compare it to what you measured five minutes ago.

Spend fifty bucks on a basic Littmann stethoscope. It sounds the same as a cheap one when you play with it in the living room, but in a noisy environment, it makes a huge difference.

You should have a reference for the normal ranges of vital signs by age group and basic treatment guides because if you don't do it for a while, you forget things and a field reference is very useful.

Basically, if you know enough to use the stuff, you'll know enough to know what to put in them.

If you don't know how to use the stuff, it's best to leave it out. OTJT is not a great thing when it comes to first aid.

Make friends with someone in an ER, and get a couple small skin staplers.  Sutures take too long in an emergency.

http://www.ar15.com/forums/t_6_10/247358_Let_s_talk_med_pouches.html