I think that you can work on the hair a bit more before calling it finished. The color scheme looks good but the way you've set it up there's black likes and airbrushed color, and they don't match up. Because in places a bright highlight will cross over from one part of hair, over a black line, and onto another part of hair, it makes me wonder why even have the lines if they don't have any relation with the light and shadow. To make this finished I'd like to see you adjust thost highlights and shaded areas to match up with the lines better.