I think you could use a little bit of improvement in the anatomy department, here and there. =) You could look for photo references in magazines, or in the
internet or buy books on stuff like that.
As for your second picture, I like his serene expression and the effect the shadow has. Here are just some things I'd like to point out, if you don't mind~ =)
-He looks like he's about to topple over because his body isn't very aligned.
-There are some anatomy projects which I'll leave to the more
knowledgeable ones. =)
-His hands aren't really goint to
fit in the pockets. Try looking at some jeans magazine ads. It'll help you with the look of the pants, and maybe even work as good anatomy reference. =D
I'd love to see some more. I actually like the "Please tell me you'll stay..." one.