The first thing you need to determine is if your primer is compatible with your paint. That's why a lot of guys will only use one brand for both paint and primer, you know they're gonna work together. So what brand of paint will you be using? I use Testors Model Master enamels and I've found that Rustoleum is good, but it's a little thick so sometimes I decant it and thin it for the airbrush, but if I'm careful not to get it on too thick I've gotten good results right out of the can. A lot of guys like the red oxide primer, but I kind of prefer the flat white if it's Rustoleum.