Ryde,
The advice to check out Comb's book is good; he compiles a lot of information there. As for what gear you should use, it just depends: what fish (salmon, steelhead, summer, winter) and where and when. With that qualifier, here's my general recommendation: an 8 weight all around rod in the length of your choice - I'd suggest 9 or 9 1/2 feet and a decent quality reel, i.e. a Pfluger Medalist or better. There are times and places for lighter and heavier rods, but the 8 weight would cover about 90% of all steelheading situations up and down the Pacific coast. I used one for more than two decades and hundreds of steelhead from 3 to over 20 pounds. The two most useful lines that cover the majority of steelheading situations would be a sinktip with 15' of high speed Hi-D and a floating line. A 10' standard sinktip is next most useful. Everybody's got an opinion on leaders as well. Here's mine: I use 3 1'2 foot on sinking lines and 10' on floating lines, with occasional exceptions. I use 8# Maxima tippet with rare exceptions, those being the Thompson River (heavier) and small or spooky low water summer runs (lighter). Flies don't seem to matter to steelhead as much as they matter to anglers. Remember, any fly's good as long as it's black. I'm partial to the Skunk and Spade for summer fishing. And any bright marabou streamer suffices for winter fishing. Consider these as general guidelines to get you started, as you'll soon develop preferences of your own.
Good luck.
Sincerely,
Salmo g.