Humidity control is #1 concern. Have a good dehumidifier unit and also keep negative pressure on the building.
If at all possible, incorporate an automatic cover during the pool install. This not only greatly helps with the humidity issues, but also is an excellent safety feature.
Besides the must haves, the best thing we did is to install radiant heat in the concrete deck around the pool. The radiant in the floor heats the whole building without any problem.