the first thing that sticks out to me is that you've got a few cuts through the center of the mask that dont add to the shape.. i think that with some optimization you can model in the 4 large dents and still get the same polycount
Working on the head. The mask is optional. Prolly won't have it for the course, but I'll have it in the final render I think. He'll only bee seen from the chin up, so I haven't paid much attention to the neck and throat areas.