I spent a few years inside a paint booth, but that was a long time ago. A lot of what I'm posting is not at all exotic. It's really just down and dirty painting: in a hurry, under the worst of circumstances, and on a very tight budget. These are fotos of a tail gate we pulled from the junkyard. We sanded off the rust and filled the holes just like any body shop would do.
The process for us is 2-2-2. We started with a 220 sanding, then wiped down the surface with alcohol and a paper towel. I know about tack rags, but we were going fast and cheap. Alcohol flashes off fast and allows us to spray before too much dust settles down. We sprayed on one coat of primer, sanded lightly again, then wiped down and sprayed the second coat on.
The next part was two top coats. I rather like three, but two will do. We sprayed the first top and let it dry. Here's a picture of what it looked like. It's kind of dull really. There's a few dry spots too. Also a few rough spots we missed.
We wet sanded the whole thing especially the trouble spots, and finished with 1,500 and 2,000 grit wet sand.
Next was an alcohol wash down. Then a top coat spray.
It's not great. It's far from perfect. The worst part is pollen dust in the paint. I would have preferred to spray right after a little bit of rain. But that wasn't going to happen for a while. A buffer and some polish will correct most of this. We will be happy with this: nice and glossy and no dry spots. Another light sanding and a third coat would have made this all look brand new, but that is not our goal. This is a work truck. It will look just fine from maybe 5 feet away.
Two clear coats come next. They need not be too think. The paint job is no longer porous. Less and less liquid is needed on the surface.
We have had great luck with Rustoleum automotive paints. You get a lot more bang for the buck as well as a nice wet look.