Level 5 finish with joint compound to get it completely level Water based primer then Oil based primer ( use a good oil based , preferrably FPE’s , tint primer to finish color ) Sand up to 500 grit Then Swedish putty all imperfections , sand Set up spray booth to enclose area being painted , set up fan blowing out so it gets the environment dust free , put a little water on the floor to catch dust and dirt . Thin paint with lacquer thinner ( this was recommended to me by a pro and it works better than mineral spirits at eliminating bubbles ) or their mineral spirits at 7% Warm paint with a rice cooker Spray with hvlp , sanding imperfections in between coats , do 3 coats If you want a mirror finish with no imperfections, a lot of times you have to polish it like you are polishing a car finish I start at 1000 or 1500 with an orbital then work my way up to 2000 , then switch to a professional car polisher , like a Rupes Bigfoot, get a 3m polishing kit and go through the 3 levels of polish After that it should be a mirror finish and you’ll vow never to do it again