painting a frame

i have a question about frame painting. when i get through building my frame for the stock floor b/d i want to paint it. i'm going to use PPG automotive paint and not rattle can crap. is there anything special that i need to do to the frame before i prime the frame to help the primer stick better? i dont want the primer or paint to be running off in the floor half way through doing it because it wont stick just because i missed something