Remove as much of the external trim as possible. IE door handles, side markers etc.
If painting in a garage wet the floor to help control dust.
WEAR ALL PROTECTIVE GEAR, FRESH AIR RESPIRATOR and a full body painter suit.
Prep is the major key to a successful paint job. Sand off old paint and fix any dents and rust. Prime with high build primer, spray a guide coat then block sand. Repeat until the surface is flat.
You doing a base/clear paint job or a single stage paint job? Base/clear job can get expensive but is easier to repair the defects. Single stage is cheaper but harder to repair defects.
Base/clear: Spray enough coats of the base color to (two, thee at the most) obtain full coverage and repair any defects. Then shoot about six coats of clear. Extra coats of clear is so you can wet sand and buff out any orange peel and defects.
single stage: Shoot six coats.
Give the paint job a few weeks to cure then wet sand the paint with the least aggressive grit of sandpaper to remove the orange peel and defects. I would start with 800 wet and work my way to 2500 to 3000 grit wet. Then compound buff and polish.
The number of coats above is only a suggestion and can be less if you don't plan on wet sanding and buffing.
Here is another alternative than using automotive paint. It is considerably cheaper but more time consuming.
http://www.youtube.com/playlist?list=PLM8M0KInsWxuvVp_vXL6StHCqtmgOICH9
