Reposting with some tweaks, and adding a reference image of sorts below, done by me in MS Paint (which I'm not the best at using for this sort of thing ):
As some other artists around here may attest, MS Paint is quite capable of producing good avatars, though you also require another program such as GIMP or IrfanView to resize avatars. Paint.Net isn't strictly necessary (although it helps a lot! ).
For example, here is something I made yesterday in MS Paint (resized with IrfanView):