round the teethline of properly and its good
as for the stroke around the hair, try using the edit -> stroke option rather than the blending options stroke. might be a little more subtle
Remove those white outlines first off, they look awkward and don't look so good. There needs to be a secondary color rather than just black skin on black hair for more contrast and so people can be able to tell that it's hair at the same time. Probably making the skin a tad bit lighter would most likely be the best option in my opinion.
Once you're done, I might be interested in buying this, so once you finish it please send me
a pm. [: I'm like obsessed with every part of it, including the white outlines. I just think they
could be a bit smoother.