Timing is one of the hardest parts to “get.” Everything else could be fine, but bad timing will let the animation down. Practice and errr… time is what’s needed. The more you do, the better you get.

Anyway, here’s some basic rules of animation that might help….

Observation: Understand the core of the action, and then exaggerate it. Even a “realistic” animation has exaggeration in it. Using Pixar for example, very exaggerated, yet very realistic.

Anticipation: Almost all actions are anticipated. In other words, everything usually goes in the opposite direction before end direction. So before you jump you need to crouch/bend down. Before you kick or punch you need to draw the leg/arm back. The longer the pause in the anticipation the more the exaggeration. This is often done in the old Disney/Loony Toons/Tom & Jerry cartoons.

Watching/analysing the classic cartoons would help a lot. If you got a dvd player you can even watch them frame by frame to understand the movements.

For your specific question.... I guess just play around with the keys etc and see what feels and looks right. Also take into consideration the subject matter/theme. Is it serious or comical, because the timing will be different for each? The facial expressions and body language of the character(s) will also effect the whole action. What about the characters, what is there intent, is it a fight or a boxing match or playing around or something else? All these need to be answered before you know what is right because even technically “good” timing used in the wrong situation wont help either.