Coloring = Awesome.

I'm not sure why you think you've got issues with coloring... the skin shows that you consider the underlying structure of the face, and the mottled look of it keeps it from being airbrushy, plastic and dull.

There aren't too many highlights, which is always a bad mistake with skin, and the whites of the eyes are dark enough to show that they're recessed, without making the eyes themselves fade so much that you don't notice them. I also love that green. That's part of why I rated this high on impact; great job at making them draw the viewer's eye.

I like the hair, too. It's less detailed than the skin, which is fine on something like this, but there's enough to it that it's still interesting.

The only thing I would change is the clothing... it needs just a little more detail. That's something I'm working on myself, I spend so much time on portraits and figures these days that I have trouble with clean lines on clothing. Something you might try is using a point-to-point straight line to place your outlines, then smoothing out the corners and edges with a soft eraser. That way, when you paint your colors on top, the edges will be more defined.

Other than that, great work. I really like this one.