For traditional steelhead I don't think you can beat a rabbit or marabou leech - black or purple seem most productive but other colors - red, orange and blue work also. This works on traditional rivers - big flies such as the N Umpqua and most BC rivers
But most of my fishing is done on the Klamath and Trinity where small flies are the game - 6 is as big as I go. Here moss backs, brindle bugs and silver hiltons seem to rule in small sizes though a friend has come up with a burlap caddis with elk hair wing that is very deadly (mostly fished sub-surface). Nymphs on all the rivers if you want to go to trout tactics can be very deadly - Trinity and the N Umpqua (though they have effectively shut this down on the Umpqua by disallowing any weight on flies). I know one fellow who fishes up in BC every year on the Kispiox mostly using small nymphs and has great success.
But most of my fishing is done on the Klamath and Trinity where small flies are the game - 6 is as big as I go. Here moss backs, brindle bugs and silver hiltons seem to rule in small sizes though a friend has come up with a burlap caddis with elk hair wing that is very deadly (mostly fished sub-surface). Nymphs on all the rivers if you want to go to trout tactics can be very deadly - Trinity and the N Umpqua (though they have effectively shut this down on the Umpqua by disallowing any weight on flies). I know one fellow who fishes up in BC every year on the Kispiox mostly using small nymphs and has great success.