I have found in prepping anything I want to "strip down", getting all the grease, oils, films, and such that Westley's Bleach White is outstanding. I would heat, scrape decals, then a LITTLE laquer thinner IF needed on the GOO, then Westleys, then slight buff with formentioned ScotchBrite pad and ROCK with the paint. I have noticed many formerly "flat" paints are only now available in Satin or Gloss. My NAPA guys have me buying flattening agent ($$$$) to mix in. This hides ALOT of imperfections. AND also, a cheap spray gun and a small compressor can layout paint really well, minimizing the chance of area's where it isnt "wetted" enough and creating a dry looking spot...
Jronwood