You can basically see all the changes I made in this image. I added the same shading for the head to the jaw, it may not be entirely correct, but it should certainly not be totally the darkest shade. Secondly, the white in the eye contrasts too much with the blue, so I used some AA to smoothen that. You probably see the other changes yourself.
Now a more important problem is your light source, according to the shine in the eyes the light is coming from the left corner, according to your shading on the head it's coming from the right. (Hint: it would be easier to fix the eye shine than the shading)
