There are some excellent books out now on steelhead flytying. You could start with the bible " steelhead flyfishing" by Trey Combs which has quite a few patterns to choose from. or you could go to Kent Helvies book which I cant remember the name of but is excellent, and features some of the best in the world. Or you could take a look at my personal favorite "spey flies & Dee flies" for salmon and steelhead by John Shewey, which gives some history to some of the old patterns that are still very effective today. If you do a little research I think you will find a huge resource to work from.