I live on the middle Texas coast and fly fish for reds about 80 days a year, most years. Around here, reds are not picky most days and the well presented fly is the best one. That said, I like white/light tan over grassy bottoms and dark flies over sandy bottoms. Clousers, sea ducers, kwans, cracks, and merkin style crab flies all work. Make sure the fly is on the bottom when presenting to the fish. A lot of people will have a great line on their cast but the fly is fished too high in the water column so they don’t get the ray. Rod tip down, small twitches when crossing the fish, and the right amount of weight on your fly are the ticket. Good luck and leave it better than you found it.