Cast a spinner well above fish you spot in riffles and on redds and let it swing downstream in front of them. Make your own by splicing a loop at either end of a section of lead-core fly line, or buy them ready made at fly shops. Carry lead links in a range of lengths for different depths and current speeds. Steelhead will take a variety of fly patterns, from gaudy salmon flies to plain black or brown nymphs. Carry a selection and be ready to experiment.
Presentation is the key to getting steelhead to take a fly.
Fishing blind is less productive with flies than with hardware or bait, but when you can't see fish, there isn't another option. Concentrate on deeper runs, pockets behind boulders, undercut banks and other spots where fish rest. Get the fly down near bottom, work it slowly across the current and strike when you feel it stop. If you can see fish spawning or holding near cover, cast far enough upstream so the fly is at the fish's level a foot or so before it reaches the fish. Leave the hen alone and work on the males.