Regarding falling over, have a look at some stills of people walking. I'm pretty sure with how far forward her centre of gravity is from her planted foot, the other leg would be much more infront of her. Changing this should also help to solve the legs being difficult to read which is infront of the other.
The head/face and hands are very blobby and ambiguous. Head is also quite big (even though it's obviously intended to be more cartoon proportions, I think it could maybe be reduced a little, just a suggestion).
The main thing that I notice is the face. It is, as I said, under-formed, and lacks any significant emotion. A blank expression which seems out of sync with the intended themes of the piece (that I receive, anyway). Omitting the mouth is crippling in this respect, since the mouth is integral to many, many expressions. Give more attention to the volumes and proportions of the head and face. Here's a pretty quick edit to give you and idea:

While I was editing I noticed you have a tonne of skin colours that are very similar that you could merge together. Any colours around the same value and hue can be average and merged.
The shading really needs a closer look. I did a tiny bit (legs). Need to think more in terms of the volumes and how/where exactly the light is hitting them. Belly and arms are problems in that respect atm.