everyone has there own ways of doing it but as long as its dry has no dirt, rust, ect and you have good products you should be good. I like to use a self etch or epoxy on bare metal

but for exhaust manifold I blasted mine and used the high temp eastwood paint that is like cast iron color and so far it looks good and hasn't come off. my original plan was to do the eastwood paint then put them on the engine, paint them engine color like the factory so it will burn off the orange but look like fresh cast iron instead of rust. but I started to think burned off paint would look like crap no matter how "right" it is,