Once you’ve mastered the basics of flip turns, make sure that you continue to improve by extending the distance you get off the wall underwater by staying as streamlined as possible, and at minimum getting beyond the flags (the 5 yard section of the lane lines) before coming up for a breath. For longer distance workouts and races, flip turns become crucial to your performance!
Swimming in a pool is great, but when you start swimming, eventually you will encounter a wall. (Which is another great reason to try out open water swimming) The most efficient way to keep swimming is to do a flip turn rather than doing an open turn or stopping completely. If you are uncomfortable with flip turns, you really should learn how to do them starting from the very basics. Go Swim provides an excellent series of 5 steps to learning how to do a flip turn.