Okay, after seeing these on a computer screen instead of just on my phone, I can see there's a lot more painting touch-ups to do. Also, the teeth aren't as visible in the pictures as they are on the actual figure, so I may need to try doing a wash on them, or use a fine point to trace them out. I do have a few more pictures to post, plus I have some pictures of the 3D rendering of the skull. I did the black highlights just below the cheeks for contrast, but the more I see them, the more I think I want to go back to all white.
Skeletron, 3/4 view:
Profile view, close-up:
Render, front view, with black cheeks:
Render, 3/4 view, with black cheeks:
And to show what it would look like without the black under the cheekbones. Please let me know which you think looks better:
Render, front view, all white:
Render, 3/4 view, all white: