First, I am by no means an expert, but I can tell you some of the principles that I've learned about low-water flies (mostly from guides and other, more experienced people):
(1) The water is probably too low for a sink tip right now. You'll hang up everwhere. Use a floating line and a longish leader.
(2) Leaders: Use a leader that is at least as long as your rod - especially if the water is ultra-clear. The murkier the water, the shorter the leader requirement.
One can buy commercial tapered leaders. For low-water flies in ultraclear water I use Rio 9 ft leaders tapered to 8 lb. To that I tie on another 3 ft 6 or 8 lb test tippet.
I also tie my own leaders, especially when I'm throwing heavy flies. The commercial leaders I referred to above, stiff tho' they are, just do not turn over a large, heavy-hooked fly very nicely. See http://www.speyshop.com
for a link on how to tie your own leaders.
(2) Fly selection: A general rule of thumb that I've used is that the bulk and transparency of the fly should be proportional to the water clarity. For ultra-clear water, I use patterns that are little more than a hook with some bright thread/floss and little hair/hackle. When water visibility is degraded, for example less than 3 ft, I use more heavily dressed flies (e.g. spun marabou).
(3) For Steelhead, you'll want to use fairly heavy tippet (6 to 8 lb is common). But, if you hook into a chum, the 8 lb probably won't cut it.
Hope this helps. Please understand that there are as many approaches to line/fly configuration as there are members on this board. Try 'em all.