Kyle had an excellent list but I would make the first step, "Clean the workpiece with Prep-Sol wax and silicone remover". You want to do that before any scuffing or sanding so contaminants don't get worked into the surface. Rather, you want them to get dissolved and carried away by the solvent. The proper way to clean with Prep-Sol is to wipe the workpiece down with a very wet rag then, immediately remove it with a clean rag. I do it with one rag in each hand. If you let the Prep-Sol dry on the workpiece, the contaminants will still be there.
The pinholes will drive you nuts. You can think you filled them all in but, after you sand and primer again, more will appear. Don't get discouraged - that's just how it goes. The high-build primer will fill some of the pinholes, but others just get "bridged" and will reappear when you sand. Some people use a small roller or a squeegee to apply the high-build primer to drive it into the pinholes.
I have used Evercoat polyester glazing compound and a razor blade with good success on pinholes.