The #1 piece of advice I can give you is to get the paint I used. The paint store lady swore by this, and boy was she right! I guess she works there for a reason. I did nothing to this door but wipe it down with some light soap and water. No prep, no sanding, no priming. As a matter of fact, there is no priming needed for this paint. I only bought a quart of it, and it has lasted through the back door, my barstools, and most of my bathroom cabinets. I still have about 1/4 left!
Add some painters tape to the hinges of your door instead of removing it when you paint. I don't know about you, but I have yet to get ANY sort of door to hang the way it did before I removed it to do the painting.......D.