Right now the outlines around the eyes don't have a clear purpose - they're not making the edge between skull and socket smoother, and they're not defining them either.
Either you darken the inside of the eyesockets and remove the banding, or you darken the outlines, is my advice.
Also the eyes and nostrils really do feel very big for the shape of the skull. On the other hand you could try enlerging the head from here, I think that'd look good as well.
One thing to keep in mind is that even if you aim for something not entirely realistic, if someone says it looks off, then it does for that someone. Keep that in mind, you can't always fend those kind of comments off by saying that 'it's a style thing'
Just saying!
Good luck with this though. Your lines are strong, but your rendering is a bit lacking. ... I'll make you an edit

Err. Everything that looks sloppy is, I'm just trying to show you how you can model and sculpt out the shapes using shading. That's all! Ask me if anything's unclear.
I added teeth and eye glow for shits and giggles, am not very serious there.
Note how I darkened the spinal cord so the contrast between spine and skull is clear.