Drawn to Life volume 1 by Walt Stanchfield is a book a lot of the top pro comic artists swear by. It's a collection of lecture notes from the legendary animator who trained the team of young animators who would be behind the Disney renaissance (Little Mermaid, Aladdin, Lion King etc).
It's very free-form, and it's not necessarily for newbies, but if you're already drawing your basic anatomy, perspective etc. to a reasonably consistent level and want to know how to really add expressiveness, polish, impact and weight to your work, this is probably the book you need for it. It's all about acting and expressing motion and feeling through your drawings.