Keep It Deep
Most fish, whether they are trout, warm water species, or even most salt water fish, spend most of their lives near the bottom. Dry flies are obviously great when they are working, but because fish are on the bottom most of the time, the most effective way to present a fly is to get a nymph, streamer, and other wet fly down to the fish near the bottom.
Use heavy weighted nymphs or plenty of shot to get them down. With streamers use a sinking line or sink tip line, possibly with split shot as well, to keep them swimming close to bottom.
Make it easy for the fish to eat your fly by getting it right in front of them and you should catch more fish.