A couple of points I'd like to add.

First, figure out what your final finish is going to be and work back from there. Many great painters mix different brands and products, but for the guy that has little experience and is not used to a bunch of different products and how they react, you are better off going with a single brand. It's all designed to go together and the paint rep will be much more willing to discuss start to finish if you stick with one system.

Second, get to know your local paint rep. Just like a good doctor or grocer, find a person that you get along with and trust and follow their advice. They will be able to help you with any issues a lot better than most keyboard jockeys (even the great painters here!) since they will know the products, local conditions and really want you to succeed. A great paint job helps them sell their product and service. A bad paint job and word of mouth hurts them.