Here's what we did four years ago when we moved into this house with a pool with my daughter who was 2 and my son was 7.
*The yard was already fenced.
*The night we moved in, we put a simple hook and latch closure on the door to the outside at our arms' reach height.
*Immediately installed 4 foot child safety fence with SELF CLOSING, SELF LATCHING GATE. This was an extra $400 and worth every penny. The gate latch was high enough and hard enough to open (must pull up knob and pull gate toward you to get in). What I was told was that as my children grew my older child and/or friends might not close the gate as they came in and out of the pool, and when you need the gate closed you don't want to think about it. The cost for the fence and gate was about $3000. A lot of money, but worth every penny for the peace of mind.
*Locked pool gate when pool was not in use, hid key on high nail in garage.
*Reviewed pool rules on safety websites and followed them, especially during parties. (Have something that the responsible adult actually holds to take turns with watching the kids during a party.)
*We had no pool furniture around the pool deck light enough for a child to move over to the fence to use to climb over. Still don't!
*Kept my daughter in a swimming vest with a crotch strap until this year when she was certified "pool safe" at the end of private swimming lessons.
Most of these things were easy to do, and became habit.
Let me say that we LOVE having a pool, it's such fun and a healthy active way to spend the summer. And great for family play time.
Just do the things to make safety as automatic as possible, then enjoy!