Unless you have an air compressor and an inside space to work on this at your leisure I would not suggest you try it yourself...to do it right, after each major stage of primering.. which is where you get the finish really smooth, you must leave it about a week to dry. Each time you spray the primer,,, the medium soaks into the primer you already have on the car... so small differences in the thickness of the primer on the car will absorb different amounts of the new spray medium.... AND SWELL. But they swell at a constant rate for the thickness ... thus,,,, a spot which was low... and you have applied more primer there... probably as a thick goo with a plastic squeegy... will swell to where IF YOU SAND IT QUICKLY when it lets go of that medium to the atmosphere (dries) IT WILL BE LOWER THAN THE REST OF YOUR PAINT. This is a very slow job to do it at home... but it is possible to get a custom car show finish with just elbow grease... You can actually put the paint on with a brush if you are willing to put in an extrodinary amount of sanding afterwards.... but you would have to be in dire straights, or a masochist to do that.. but the point is that it is the careful sanding all through this process, given that you are using good compatible paint, that is most important.