Thank you! That's such a flattering compliment.
I really appreciate your kind words.
As for anatomy, all I can say is to look at real people/models, etc. My anatomy is far from perfect and is usually quite stylized and exaggerated... but I generally always try to look towards realistic reference in order to get things looking the way I want them. 'Human Anatomy for Artists' by Eliot Goldfinger... Or any of Andrew Loomis' books are helpful! It's great to have some basic understanding of real anatomy so that you can make cartoonish anatomy appear solid and believable, despite it's exaggeration.
As for expressions, its really the same advice. Look at references or at yourself in a mirror. I tend to work very loosely in the initial stages of drawing so I can get the expression I'm looking for.
www.lackadaisycats.com/exhibit… <-- Here's some great advice (in a much better and more visual way than I could give!)
I hope this helps a little. Thanks again!