How to prep roof for paint?

Ok so...
Repair metal where needed
Acid wash/metal prep (what kind? So many options)
Epoxy primer over bare metal
Body filler and seam seal where needed
Primer over body filler
Paint

Can I paint over the factory paint if I prep it right? Sorry for all the questions, just want to do it right. I did a short stint in a body shop, but that was 25 years ago and I don't think what I was taught was correct.