I agree with Jakers dude. Your drawing skills are nice, you have confidence in your lines. You do need to study from life though. I just added these books onto another thread but here:
Force by: Mike Mattesi
Atlas of Human Anatomy for the Artist by: Stephen Rogers Peck
Grab these, and study from them. If you are able to take a live figure drawing class, snatch up the chance. You are looking good dude, you top figure has a lot wrong but its easily corrected. The bottom figure needs a little more cranium on the back of his skull. But other than that, keep on practicing. Peace.
"My other pen is a pencil"