Please xcuse me if I repeat something Amerasu said 
I really like most of these, so I'm just going to list off my crits:
1. You have the folds down right - a good concept of how the fabric is interacting with the light, but your edges look slightly, and unnaturally, soft. Sometimes it's appropriate, but others it isn't. Also, it'd be nice to see a lighter color for highlights in the bottom half (as opposed to the neutral gray throughout most of the fabric.)
2. I'd suggest working more to define form, as opposed to leaving it implied. It's pretty obvious, but keeping the entire drawing at the same level of "finish" makes it look much more "professiona." I'm thinking specifically of the head and legs.
3, 4. Maybe work a bit on line quality? You seem to restroke a lot, and on the first it's used to good effect in the outline, but othertimes it looks fairly sloppy.
5. Hehe, very funny. No real suggestions here.
6. The anatomy here is a bit worse than the the other drawings, especially in the neck and head.
7, 8, 9. I'd work on giving the pieces a less muddy quality. Try defining the different areas in short, quick, more assertive, strokes. Right now you have many of the same sketching techniques going into these, but the end result looks much less clean.
10, 11, 12, 13, 14, 15, 16. I really like these alot. Especially 10. No real crits. Just, again, work on line quality.
17. My only crit is that the work isn't very "crisp." The same proble mas in 7/8/9, etcetera.
18, 19. Both of these are very good. Much cleaner, and more defined.
20, 21, 22, 23, 34. I don't like these as much. It looks like they were from observation, but general perspective rules were disregarded.
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