This is NOT a real pixel, I did it in GIMP (following this tut) but I think I can still get some C/C on it, yes?

 

 

Mostly on the shading, I know it's crap... I suck at shading, so halp plz?

The shading looks fine IMO, but perhaps a little dithering would make it look better?

A pixel doesn't have to be made only in Paint.

 

A pixel doesn't use filters or any of the tools associated with more powerful programs. If you haven't used any effects then it's still considered pixel art.

Clean up the linework, it's choppy.

 

 

 

Dithering. Useful for shading but also useful to show off the texture of an object, in your case a wool hat. Currently it looks metallic almost. Just go look at a real hat and see how light falls on it.

Yup, some dithering would really help it. Right now, there's too much contrast between the different shades of green and there's no sense of texture, making the hat look a bit like it's made of glass.