I prime my models with Plasti-kote 'sandable' automotive lacquer primer. Comes in a spray can, I use the 'gray' primer. If by chance I get it on too thick I strip it off with Easy-Off oven cleaner, and then re-spray. Been doing it for years , and, I guess have gotten the hang of it.
Glenn
p.s.- I prime plastic parts, white metal parts, P.E. parts, whatever with the lacquer primer