what is the proper push-up form?

If you are interested in what is officially required, at least in the Air Force, check out this site: http://www.afpc.af.mil/affitnessprogram/index.asp It has videos as well.

They are extremely picky on form during your fitness tests in the Air Force, don't know about the other branches. But make sure you are doing it correctly either way.

Hands spread slightly wider than shoulders, fingers pointing in whatever direction feels most comfortable.

Turning fingers inwards increases pectoral work, pointing them forward puts more pressure on the triceps.

Keep entire body straight including head, look to ground.

Breath in before start of push-up and exhale as completing the push. The only part of the body that should touch the ground might be the chest. Otherwise lower to just before any part of the upper body touches. There are many variations; widen hand position, narrower hand position and variations of direction of fingers to put more work on different parts of the upper body.

Depends on what muscles you want to work. In general you want your hands just wider than shoulder width and parallel with them. Basically you want your shoulders on top of your hands and then slightly wider. Then you want your feet together and back straight, no bending or sagging. When you go down your nose should touch first, unless your a woman.

Here is a link:

http://www.wikihow.com/Do-a-Push-Up

jumping push-ups work the best and you cant get the wrong.

arms should be spread out only as far as your shoulders, and keep your hands just below the breast-level.