The surf action can lead to slack in your line, especially when fishing with a floating or intermmediate line. Make sure you are in contact with your fly. Casting parallel to the waves can also help minimize this.
Look at a beach at a very low tide, and make some notes on the structure it can reaveal. Keep that in mind when you come to fish. Finally, if you look closely at the surf you can find currents. The wave action will meet at some point, this can be a 'ho
t spot'. Also, the wind and long shore currents (currents moving down the beach parallel to shore) can concentrate bait and fish.