Start by getting a couple really good books. Read them cover to cover. Then come back with a ton of questions.
The conscientious Marine Aquarist is a good one to start with.
Just finished reading this one - 101 Best Nano Reef Species by Scott W. Michael. Covers max size at adulthood, minimum tank size, feeding, compatibility with other tank mates, symbiotic relationships between fish, reef and even shrimp and fish pairs.