I'm a big fan of the 2" wide blue masking tape. I have never used any primer, and don't really see the need for it. I usually only spray two to three coats of color on my cars. Some types of paint will let you get away with it (Tamiya), some will require more thin coats or else you'll get runs (Testors). The only car I've sprayed clear upon is the 1967 Corvette I just did. It came out really nice, except for the dust and cat hair that got into it.