Here is some advice:
  1. Call 5-6 pool builders that have less than 5 Better Business Bureau issues in the last 36 months - and that any issues have been resolved. Ask the company what the issues were reguarding and what they have done to make sure the problem doesn't happen again. If they have 15 and they were all "impossible customers" - I would run in the other direction!
  2. Ask each one the same question - what is better? It could be that a certain type of pool is better for the environmental conditions in your area. In Central FL, it was recommeded by every pool company to go with concrete. Also if you want something you can totally customize - a pre-fabbed pool may not be what you want.
  3. Never ask a pool builder to install a feature/type of pool they don't normally do - you are certainly asking for trouble. Don't insist that a company who installs 100 concrete pools a year and only 5 vinyl pools install a vinyl pool in your yard. You will be able to tell when you talk to the sales people what they don't like to do - or don't do often, because the sales people will tell you why you shouldn't do it or they will seem less then forthcoming with information about a feature they don't normally install.
  4. Don't pick a pool company because you like the sales person or because its the lowest price. Pick them because they have the best installation for the money.
  5. When I looked into pool companies - I drove around and found people that were having pools installed by each builder I was looking at and knocked on their door to find out if the builder kept time lines, etc.

Most of all - good luck. As with any construction project there are always problems and set-backs, but a good company will keep you informed and work with you through the whole process!