I used PPG for almost 20 years with excellent results. I highly recommend a moisture trap. I used a Binks touch-up gun for large areas and a Pashe airbrush for trim. 3M fine line tape which was kept in a sealed plastic bag when not being used. As for bleeding under the tape: everything said above can contribute. I used to clear coat; so slight imperfections along tape lines could be sanded out. In an effort to save a bit more weight I stopped clear coating. To help prevent 'bleeding' I would trace along the paint edge of the tape (before painting trim colors) with the back end of an X-Acto knife handle to ensure good adhesion. The Pashe airbrush prevents spraying excess paint and requires several passes to get get acceptable coverage.
Good results with spray paint require good technique and knowledge of the paint being used. Good equipment helps a LOT. I've done some auto painting and I think it is safe to say that quality guns can really make a difference.
I'm going back to epoxy paint (Klasscote) which seemed to be a bit more forgiving though it has been 25 years since I used it. Hopefully, the changes in formula (to meet EPA regulations) have not changed the application ease.
A great paint job is really rewarding!! A crappy paint job is a lot of sanding...[]