I understand that you may be going for an old school look with the black color outline, but it looks bad imo.
You need to use a dark brown color for the skin outline and maybe a red for the hair, you also seem to be exactly following your outline for the face and sometimes hair with your shading colors which is a bad idea, i don't know the term for this.. forgot.
here's a picture to show what i mean, i only have time to work on the face a little but take a look at it without the black, and without that shade problem i told you about, i marked it red where i took off some pixels.
Another thing you need to work on is smoothing your linework, it's too choppy in some spots like hair falling around the left side of the head for example, and she looks like she has a long slender neck it seems so you would not see the collar bone really.
