We did use other fly patterns and had spotty success with those, but the clear winner, the real go-to fly when things got slow, was the simple Clouser saltwater fly. It was by far the most productive, whether on the beach, in the surf, or on the boat; whether in 6" of water of 10', it was always the first and last fly we would try.
I tie these flies very sparsly using white bucktail, red or yellow lead dumbell eyes and pearl tinsel flash. They don't look like much, but simplicity must be the key because they are the most effective fly I know for all species of fish. I usually add a weed guard when fishing the grass flats.
The retrieve is a quick 6" strip, with a two second pause and then repeat. Strip all the way to the leader connection, since some fish will follow the fly a long way before striking. Fish often take the fly at the end of the pause, so maintain connection with the fly line at all times.
If I could have only one fly to fish with, it would definitely be a white on white #2 Clouser minnow. These are pretty difficult to find since most Clousers come in 2-color combinations, but I tie these myself and they are available at http://www.flatsfishingflies.com/ under the heading "General Purpose Flies". Tight Lines!
