Aw man, NaCl beat me to the punch. I did a quick edit here for you also to give you some ideas.
Pulled both his shoulders back to give him a more natural pose (as NaCl mentioned).
Added a few colors plus some shading.
Nixed most of the interior black outlines--This helps a lot in giving you more room for little details, the black lines running everywhere really break it up and take up a lot of sprite real estate without actually contributing much to the details of the sprite.
Rearranged the feet a bit to give him a more solid stance--it would need to be fiddled with a bit to give him a run or walk cycle.
Gave him some yellow rubber boots, just because he looked like he needed some.
For some reason, it makes me think of South Park. Not sure why. Maybe it's just the whole little kid dressed up for winter thing...