Obviously like everyone else says prep is everything, skim coat filler and lots of blocking.
I use Sherwin Williams paints mostly 3-4 coats base, 3-4 coats clear. Sit for couple weeks before i cut and buff the allow for any shrinking then cut with 1500 and buff using 3m perfect it compound, mothers swirl mark remover and finally polish out with 3m Finesse It Polish.
Heres what it looks like after;
Im 23 years old and have only been painting for about a year consistantly and if I can do this I think anybody can lol