well depends on what your using. i assume you are taking powerbait? if so they way i usually do it is i take a couple split shot and put em about 18 inches or so from my size 6-8 single hook with two chartreuse powereggs.
for bait I really have done well using the berkley "power nymph". Rigged the same way that beaverfan does. I like the size #6 Owner mosquito hooks.
I like the power nymph because it has the same scent as powerbait, much less mess, and the way it is shaped is a suggestive bug and if gets them to bite even when jigged or casted and retrieved slowly. Also until you get one that swallows it all the way (does happen often if you leave it holding still) you get it back so you are off to the races again quickly.
My most used trout rig is a small spinner (size 2 or smaller) tied directly to 4lb mainline. casted and retrieved and sometimes twitching it on the retrieve.
I recommend a slip bobber set up; drifting a piece of nightcrawler, you can adjust the depth in an instant and not have to worry about having to much line between the bobber and the bait. A slip bobber elevates this issue...very productive presentation for Trout..at least it has served me well over the years.