With summer here (in Australia) swimming pools are a scary thing for a parent.  Your children want to go in the water, but pool safety is such a big issue.  My children are 4 and almost 3.  The first thing I taught them was not to run in the pool area.  My kids know that if they run near the pool, they will be put out of the area altogether, and won't get to go swimming with everyone else.  The reason I taught this first, is that accidents happen so easily, and I don't want them falling in.  They have always been told to kick to the surface if they fall in, which helped my eldest last year, but sometimes fear takes over, and we don't think, this way you are at least helping prevent accidents from happening.   I must sound like a nagging mum a lot, but when it comes to the pool, I repeat and repeat and repeat the rules of being near the pool. 
No running
No going in the water without swimvests (yet)
No pushing or mucking around, near the edge of the pool
The last thing I want, if for one of my kids to go before me, especially from a drowning that could have been prevented.