Well, needs a fair bit of work in various areas. I'll just list them in bullet form.
- Hair: You should work on shading hair, basically it involves layering up different shades (a smudge stick is good for this) and putting in the highlights with a sharp eraser.
- Eyes: Though the reflection in the eyes are nice, they are seriously huge eyes and definitely need some work on the shape (just study eyes in general and you'll see they have a completely different shape).
- Nose: Try to work on using shading (especially cross/multi-hatching and a smudge stick) to work the form of the nose rather than drawing it out like that.
- Lips: They look too solid, it's really just a matter of getting the general form of them with a light pencil and using shading techniques to get the overall look of them.
- Head: Well the head looks like it has a fairly funny shape. Try drawing it as a skull in a light pencil and then start filling it in (at least this works for me).
- Shading: I think you'll find that your drawing will absolutely come to life if you practice some cross/multi-hatched shading or at the very least layer the way you shade so that there isn't such a clear definition of dark and light shades -- it's good to just study people in real life or photos and see how light bounces off and shades their skin.
Anyway, I hope I'm not a jerk, just thought everyone else gave nice "comments" that I'd be a bit more helpful.