OK! Let's do this~
1. Looks pretty good! One slight suggestion is the line that makes up the outline of the face looks a little off on the left side, it makes the left side of the face look a little bigger. Other than that, it look really good~ :3
2. This one's also good, just make sure the neck lines are straight! No one likes a rubber neck while they're driving or in drawings~! (My failed attempt at humor... ORZ Sorry you had to read that...)
3. I really like the folds on his sweater! Great job~ Two things; one, his left (the one on our right) looks more muscular than the other, and two, his left (also the one on our right) leg is slightly thinner and his shoe/foot placement looks a little awkward to me. ^.^; Other than that, you're awesome!
4. Awesome profile on the face~! Looks great n.n~ Ok, first thing I noticed was that he looked thicker from the neck down, but when you get to the torso, his legs look kinda thin, and that the leg farthest from us looked a little awkwardly placed; a little too far out maybe? Other then that, you did pretty good~ :3
I really like your typography and I'm not really sure how to crit that... Heheh~
Hoped this helped somewhat~! If I critiqued something about your style that is just that, your style, then please, IGNORE that part! I don't want anyone to change anything about their style that they like just because I said something~! Welp, it was fun~ :3