Larry gave great advice on drawing the face.
Everything about the body is proportional and it's quite amazing.
The eye is not a football. It is a ball --2/3 covered by lids. You need to
show how to wrap that lid around the ball.
Drilling the proportions of the face and the body is just that-- a drill.
Once those proportions are understood half the battle is won.
Did anyone see the John Cleese special on the Discovery Channel about the
Face? I missed it, but from the web site, I get the idea that the
proportions of the face were very well documented.