Yup. Anticipation, secondary motion and follow through are also important to making animation look good.  Remember to bring the action through the entire body and not just the body part. Then, make sure the action completes before begining a new action or the overlap may cause some confusion (this depends on the situation though).  Back in my Amiga 500 days I had the Disney Animation Studio - the manuals and examples that came with it were like a course in animation by themselves.  No program has ever come close to giving you clear examples of basic animation principles in-app.

Sadly, we have yet to implement any kind of squash and stretch features in the bone system so that has to be done manually by a combo of morphs and scaling. May not be as important if you're working with "realistic humans" but if you're working with toons, that's kind of critical.

Required reading: The Animator's Handbook.