Hello, I'm just going to give your a crit on your second one, because the first one seems to be mainly in your own style while the other is more rooted in figure drawing
I have done a draw over
http://oi57.tinypic.com/29zpqfs.jpg
I must say your proportions (8heads) is actually pretty accurate, but there is not as much attention for the important muscle groups.
The main trouble area's are at the crotch and the armpit, and the size of the head a little. I think alot of your problems can be solved by learning the important muscles
I would recommend you to get a few books on the subject because it's easier to learn from the start then dive straight into drawing from reality.
I would recommend Andrew Loomis Figure Drawing for all It's worth, and Michael Hampton's book
good luck :)