[spiffyflypie]

Notes:
Hair is voluminous, yes, but not quite as much as you had it.
I gave the ponytail(which I'm assuming is supposed to be at the side, as opposed to the back) a bit more curve and shape.
I did the same for the bangs/fringe, and remember that the center portion of hair shouldn't be too straight, and looks best if it's nice and long.
The eyes were a bit close together, and shaped a bit funny. I added eyebrows.
In anime, the nose is usually sort of a vertical line, but I think a curve looks better.
I reshaped the jaw and moved the mouth lower, but otherwise the shape of the face was fine.
The neck was a bit thick and short, so I made a thinner neck and made the shoulders less broad.
I also reshaped the, er, upper torso.
Hands. Hands are usually the trickiest things to draw ever, and it takes lots of practice before you feel comfortable with them. However, hiding the hand behind the back is sort of cheating, as you do not get the practice of drawing it. Besides, it's sort of an unnatural pose, unless you're hiding something. I look at my own hands a lot when I draw, just to get the idea of it.
The legs only needed a tiny bit of editing, and I really can't help with shoes because I'm still getting the hang of those.

Hope I was of help ^.^