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at the moment, you have his arm's muscles too far down, which really isn't a difficult fix.
the bicep is too far down, which would normally make bending his arm impossible because it was lined up with the elbow. the forearm looks good, but the hand makes it appear like he has two fingers. by making it slightly wider and trying to show more fingers, even with just a few pixels, might help.
His stance indicates that his right leg is stretched to the side, which would lower his right side unless his other leg was either the same position or bent at the knee. Souly got to the other arm already, but I edited it in here anyways to show how it might look. His pose also suggests that his stomach is facing forward quite a bit, so his back should be at an angle. If you decide to move the arm up you might also want to stretch it out a bit...hope this helps.
-it looks like someone posted while i was writing this. their edit fixed up some things too..oh well.