I haven't shot a car or worked in a shop, so take this as dummy input.
I'd find a GOOD local paint store and ask questions. Mail order stuff is just as good, but you will want local experts to answer all the questions, and they deserve your business after answering all the questions! They will more likely have extra materials on hand in case of any issues.
Find out what brand you want to use from bare metal through the top coat. If you mix brands, the finger pointing will start for any issues. Leave mixing brands for the experts.
Once you have selected a brand system, find out what the time limits are and how to prep between coats. Figure out if you can meet these limits before you even start. Plan ahead! Even ask if there are guide coats to be avoided!
Ask the store if you get a better deal buying it all at once, or not. See if there is a cash discount.
Most pros have different guns for primer (it's abrasive) and color. Ask about that and cleaning supplies too.
Be safe! Many modern paints, catalysts and solvents are very bad for you. Make sure you understand and prepare for the risks.