Mofo, you'll generally get a crisper picture if you shy away from the imprecision of the paint tool. That thing just plain sucks. Try outlining with the line or pencil tool (which both have a few different settings to play around with) and then filling in with the paint bucket. If you're trying for a more cartoony look, just make shapes and edit them how you need.
Paint tool works great! Just spam the Smoother icon a few times after you draw each body part.
Actually besides the hair and a few missed spots on the arm and torso, it is decent. His pants look very stylized.
Try putting each segment of his body in a different layer. That way you wont have those problems between the back arm and the torso (it looks like his back arm is sorta blending into the shirt). The layers will be a help once you are ready to animate too.
Regardless of if you are going to animate a picture or not, its always best to use layers:
http://www.layoutgalaxy.com/html/htmnewletter51-page2.htm
Hehe, oh boy. Mofo, hang out on #soldat.forums and I'll help you out and show you some good tutorials and help sites that I've colleced. That goes for anyone else who is interested in this stuff, too -- I can help you out with anything from animation to actionscripting, and if I can't, I can direct you somewhere to find out.
Edit: Would enough people be interested in a mini-flash tutorial to actually warrant making one?