Uhhhhhh...

Very nice use of color. However, if you look at it from an angle as if the person was standing straight, the nose seems to be very long. Also, the highlights in the middle of the hair aren't too noticeable, which is good, but I suggest spreading them out evenly with the rest of the hair. I also suggest trying to make the hair slimmer. As in reducing the amount of hair, and having it look sleek, or tied back. The shading doesn't need improvement, it's very nice. Overall, it doesn't need much improvement, since it's nice already, these are just suggestions.