more detail in the hair, maybe add some kind of shine/grayish effect.
For the eyes, the white sparkle need to be parralel, so for example, the right white sparkle need to be on the right side of the pupil instead of on the left side.
Continue to make skins, I see you have a good sense on how to make them
Seems like naruto in a way in kyuubi form... If it is naruto great job since you should start from dark color and color in the light color to add details in hair.( same for the contrast)
And also try to save a image of it with only the hair... No eyes no nothing. Since it will be easier for you to draw different kinds of faces rather than erasing the previous face in the same image. And lastly when adding contrast, i preferably make the left side of the face darker and right lighter. Anyways... Good luck :p