I have to agree with 1337. Except that I will usually do 2-3 mist coats before applying wet coats. While your in the mist coat stage the model will look pretty ugly. The surface will look a tad rough and transparent. After the first wet coat it will all disappear.
If you apply to much paint in the beginning it has nothing to stick too. Therefore it just runs off any sharp edges and panel lines. The mist coats provide a "tooth" for the paint to stick to.
FSM had an excellant article on this very subject a few months ago. December 2003 issue to be exact. "How to get great spray-can finishes by Matthew Usher."
Darren