I always try buffing the worst part of the car, then decide. I also try the least aggressive stuff I have first, then progressively go to more aggressive methods if it doesn't work. So...try wax first, if it doesn't work, go to a liquid polish or swirl remover, then a more aggressive liquid polish. If still no-go, try a fine compound. If no, go to more aggressive compound, or try sanding with 1500. Then 1000, if still really bad, you could try 600 or 800, but at that point you are removing paint pretty quickly and if there's not a lot of paint on it, it will go to primer . The you HAVE to paint!