Automotive Paint -What can't you mix? How long can it store?

What 440 abody said X2. I am doing my own body & paint and I have a lot of experience and it is still hard for me to get it right. If you have to do it yourself, find a friend with experience and pick his brain. Then you will have a shot. So far for mine I have bought epoxy primer, european primer polyurethane single stage color, clear, gun wash, all catylists and reducers and still have to by the sealer I will shoot just before color. Do your homework and get good advice and you should be fine for your first time. Best of luck!
Rat.