Have you tried looking at tutorials? They'll teach you the basics of outlining and shading.
KawaiiHannah : Pixel Tutorials, Folds Tutorial, Doll Base Tutorial
Kawaii Hannah gives you a nice idea of the basics to pixeling, like clean lines and such. ^^
Another good site for the basics. Watermelon is a little wordy, though; be prepared to read a paragraph or so.
T h e ** D o l l e r y ****
The Dollery has some nice specialised tuts, though some of them includ graphics that MS Paint can't do, though they're still a help with how some tihngs should look.
And there ar emany more tuts to be found! A lot of base sites provide them, actually. While just learning shading, it doen'st mater if you don't have your own shading style yet; you'll develop that as you get better.