I've got to second (third, fourth, fifth?) most everyone else, you could really benefit from even just some passing anatomy work. Don't try to rush in all at once, either. Start a sketchbook thread, something you can put work in every day, and focus on one certain part (the arm, the hand, etc), trying to figure that part out at little more.
Examine yourself, people around you, and pick up some source material (Loomis is free online) to look at and draw from. Books you can carry around and if you don't feel like drawing, pop one of 'em open and just mull over the information and instruction in them.
"If something looks too big, make it bigger. If it looks too small, make it smaller. You're dealing with fear here, not right or wrong."