You must be aware that sometimes it is difficult or unrewarding to post constructive criticism on certain pieces, for various reasons. Either the pieces is good as it is and nothing constructive/educational/demonstrative can be said/done about it, beside doing it in a different style. Sometimes we lack context for certain pieces of pixel art and would be able to suggest/comment better if we saw it inside the game environment, beside other game characters or maybe animated. Trust me, when you get no response but obviously are producing usable art, keep working. Don't let the lack of response hold you back. If you are doing something obviously wrong, I'm deeply convinced a skilled pixel artist will point to it. Unless when a noob posts something he aborted in 5 minutes. Some things can't be helped. But this is not the case here.
For this very piece I would suggest trying to express fingers on the fists if possible. I would definitely like to see him in some context. Eyes contrast quite nicely with skin tone, IMO.
