Seriously. You should try it. It only takes a few minutes... and your soul!!!!
But, seriously, it's a matter of practice. Anyone can do the basic stuff, but it takes a while to figure it out. Even the best avatarists around (a group which I am by no means a member of) are always getting better.
Overall advice, get Inkscape or Sodipodli and crack open a few how-to guides. Serpentine's right about the overall progression. If you don't want to get shot down, try making a webcomic in the style instead. You won't get shot down, it's just that nobody will read it.