Yes I'm so vain I just HAD to pixel myself.  But I want it to be perfect!  I'm having issues with the shirt and the expression (and maybe the hair could use some work?).  Any constructive criticism is greatly appreciated.  Here's my reference shot.

Quite a nice start; the face looks good and it doesn't have any BLARING anatomical issues (the only kind I would ever find, lol). I suggest a few things: first, the shirt has a few rather jagged areas; use the intermediate grey to aa the light and dark stripes. Second, use antialiasing LIGHTLY all over; the facial outline and the outline of the shirt would benefit from a little bit of smoothening via aa. One last suggestion that you might or might not want to try: extend the ditherpattern the opposite direction as well.

Looking good; one thing that I'd like to say, though, is that instead of antialianing AROUND lines, try going ON lines with lighter colors. Doing that will never give the blurred effect antialiasing around can give. Now what you have here is quite nice and far from being blurred. But it might still be worth it to try the other way, just to see how it'd look.