Realizing of course that you are still working on this guy, I think you can smooth out some of the darks that are under and between the eyes and nose. Also, around the nose, forhead and cheek bone, these areas look a bit muddy. Some of this maybe because it looks like there was a shadow cast on the fig. when you took the photo, and its a little out of focus too, so its difficult to say. You're making good progress and I look forward to some more pics.
Joe