In addition to Ard's always wonderful advise, are you fishing on a stream? It's much easier to pull a fly of any sort out of a fish's mouth if you are upstream of your fly. Casting upstream, or across the stream, to a fish makes hooking them much easier. Sharp hook points are a HUGE help. Try dragging your hook point across your thumbnail. If it skids across the nail without catching, it's too dull. I tie my own flies, and use quality hooks, but check for sharpness before and during fishing.
My wife suffers from premature hook-set-itis.
We were fishing little hopper patterns this past Monday, and she'd jump a bit each time a fish took a swipe at her fly. It's always exciting to see topwater action!
Billy Connolly Teaches his Nephew Dry Fly Fishing (R-Rated for language):