for the girlie with backpack:
things are off with the shoulder. I feel like it's too thick, I think, but I could be wrong.
Like moe said, it's a bit skewed, but i didn't really notice it until moe pointed it out.
I think the head's a bit big, even for this caricature. If that's what you're going for, so be it.
Legs are too short. I personally feel that the skirt is located a bit down from what it should be, so I guess it should be moved up a bit.
her right shoulder is not long enough I think.
The scarf looks slightly blandish, just staying there like that. I think the scarf of our left side (her right side) could be removed without any worry. I sense a bit of a 2d feeling from it as well, maybe that's the problem.
Moderate use of shadows. It could be better used, but it's really not bad atm.
Very cute expression.