It looks like a pretty good start from what there is to go by. I actually do all my Anti-aliasing by hand in my pixel art (at least, the ones where I bother with it) and it's just something you develop a style for I suppose.
As for the lines under the eyes, I'm not sure how to describe this so I figured a visual example would be best
The one on the left looks older, the only difference between them is the lines under the eyes. They should be close together and more horizontal, I suppose. Also, the furrowed brow adds to the look I think. If you could make him look sort of "Wicked" that'd be good, that's something I am not very good at. Also, I sketched another one and I just liked the expression so yeah
A bit of blood would be good, for sure. And he definitely should look kind of scruffy, too.