donom has a great edit that I've saved in my archives. I know this post contributes very little, but I feels that he accomplishes in a few lines what I intended to say here and that the best i can do is second the advice.
I agree. I made a horrible, choppy edit while adding two colors, and Donom made exactly the look I was going for in the same style. Well done, ignore my edit.

New version looks loads better. If I had to nitpick a few things it would be A) The hair. Really, try adding highlights to it. It will greatly increase the depth, and give it some more form. B) I think maybe a few very subtle shadows on the face would be good, in choice places. C) Right now the shading on the face, where the hair starts on the right, still looks blobular, which doesn't represent the curve you've added on the left of the face. Here, let me show you:

Better? I was using Paint, so the 2x pixels aren't exact, but you get what I'm saying. Also, I didn't do this, but adding some subtle light highlights on the cheeks would give it more innocence. If you don't want to add the subtle shadows.

Really though, well done!
Toodles!
Shrike