If you google-search 'saltwater flies' you get roughly a bajillion different options. Don't buy in to the chaos. If you look, you'll notice that the guys that fish a lot are usually only using a few different patterns. When I get out on the flats I am condensed down to a single fly box that fits in my chest pocket. Bluewater and jetty fishing is more eclectic, but you can still simplify. K.I.S.S, 396 style. I've included links to purchase the flies that are commercially available for your convenience if you don't tie.
The Clouser Minnow - Tied in various sizes and weights, this ubiquitous fly is effective on nearly every species of fish you'll encounter on the Texas coast, and can imitate a wide variety of prey species. Buy here.
The Merkin - there are times when redfish really focus in on crabs, and this is the original yarn-style crab with an awesome name. Thanks Del Brown. (Also effective on black drum, permit, bumphead parrotfish, triggerfish, bonefish, etc.) Buy here.
The Seaducer - when the fish are super skinny and you have to absolutely land a fly softly like on those windless mornings, the seaducer is the ticket!
Gartside's Gurgler - my go-to topwater for skinny water fishing, the gurgler is a tremendous imitator of small shrimp flipping and popping away from marauding redfish. Buy here.
The Chin Slinky - created by my friend Casey Smartt, the Chin Slinky imitates a benthic marine worm and when black drum are in a feeding mood, they can't resist. This has been a trip-saving fly for me.
Tarpon Bunny - the tarpon bunny is another fly that is imitative of a wide variety of flies and can be tied in a variety of sizes and colors. It's got a great, sexy movement in the water. Buy here.
Surf Candy - A fly with understated elegance; easy to tie, tooth-resistant and super representative of small baitfish like anchovies. This is a great fly for surf, jetty and beyond. Buy here.