Check out these very basic rules for swimmers -- both beginners and advanced. Very basic, but life saving!
Rule No. 1 Never go into the pool alone. You may be an expert swimmer, but in case of a muscle cramp or pain, a swimming partner is your best bet. This is especially very important for beginners.
Rule No. 2 Before trying out a new exercise, make sure you understand exactly how it is to be done. Do it the first couple of times in front of a trainer.
Rule No. 3 Make sure that the chemical content of the swimming pool is safe. This is especially important for people who have a pool at home. Options like Bromine tablets are supposed to be better than the standard chlorine tablets because they last longer and go easy on the eyes. On the flip side, bromine tablets are twice as expensive as chlorine tablets. Research the market to see what works best for you. But make sure the pool is a safe place for you to swim in.