For starters, i dont recommend taking any advice from Shadow Serpent, as he not only has no idea as to how to pixel, but the majority of anything he claims to have made is stolen from other artists.

That said, The base needs alot of work, in many areas, I would suggest you look at our tutorials section, in particular, look up lineart, shading, and color usage.

The base is overly square IMO. The legs are too small and unproportional to the larger head and arms. The chest takes up abit too much space in both length and width aswell. Id suggest shrinking it down abit(raise the chest line up to make some room for the abs).

The eyes are abit too big aswell, taking up most of the space on the face. if you like the eyes, thats fine, but id suggest making them smaller by at least a pixel from the bottom, so there can be space for any mouth animation you may do in the future.

The neck is pretty thick, id suggest thinking it by a pixel on either side, which will make the shoulders look abit better, and then making the arms rounded rather than square at the end. For the arms id make them come out alittle to make the icons position look less strained, but thats up to you.

I would also suggest you increase the size of the base. It is certainly an option for you, especially considering we're no longer limited to 32x32 artwork. you'll have more room, obviously.