Well, first it should be legal; zoning, setbacks, fences, etc. See our Do I need a permit to put up a pool? section for details. You can’t build over utilities, septic tanks, and leach fields.
Avoid putting it under, or even close to; overhead electric lines, trees, plants, and shrubs. Why let wires, dirt, leaves, and fertilizers fall into the water?
If at all possible, try to put it in the sun as much of the day as possible. Watch where the sun shines and shadows fall every couple of hours for a day, and you’ll get a handle on that. It’s easier to keep your water warmer when the sun heats the pool walls. For that matter, try to avoid prevailing winds that will cool the pool.
Realistically, most people only have one spot big enough, so that’s where it’s going to go! Other things to think about: the closer to the house, the shorter the ditch for the electric outlet and the shorter the distance to carry the hot dogs and lemonade for pool parties!