It's vital to remember that a pool is just one part of the larger landscape. Therefore, it's best to use a landscape architect to design the pool as well as the rest of the site at the same time. All too often a pool contractor is employed first to design the pool without an overall site plan. The result is that your pool and landscape do not compliment one another, and you lose the opportunity to integrate options that provide more value for the same price.
Because pools are such an expensive proposition, it's important to give a lot of time to design. You'll only build it once, and therefore your choices of materials and detailing should be high quality and timeless so your pool design won't go out of style in the near future. Beware of fads. Question new materials before you invest. The rigors of weather and chemically treated water may have far reaching consequences for newer materials that have not stood the test of time and use.