Whether your character is cartoon-like or hyper-realistic, there are a few simple design concepts (okay - Tricks or Cheats) you can incorporate to make your eyeballs "look" good. Download the Seeing Eyes,Tricks to Make Eyes Look Good guide for a quick "How To."
How to setup a 2-joint knee. Getting knees and elbows to deform properly can mean many hours of weighting vertices and even extra modeling. Using a 2-joint knee (or elbow) setup is a quick way to cut through all that tedium and get back to animating.