Welcome to Pixelation!
Before passing to AA, I'd say there are a few issues to fix.
The first is anatomy: I'm no expert so I can't draw a sketch to show you a plausible anatomy, but to me the forearms look way too big; also, the abdomen looks weird because of the muscle shapes and, maybe, of the size (could be a little shorter, perhaps); finally, the neck doesn't present sharp, angled lines (or are they meant to be interpreted differently?).
Then, there's shading: at the moment the piece is heavily affected by pillow shading*. Choosing a different light direction could help you avoid that and make the piece more interesting (and eliminate left/right mirroring in the process.
*You can find plenty of explanations about it and also about AA on these forums.
Keep on pushin'!
