When choosing the right color drift rig for steelhead I try and keep it simple. There's not much use in "throwing the kitchen sink" at them. I feel that if there are fish around and you're technique is good, all that needs to be done is use a color that will show up under the existing water conditins. This is one of the most important details.
Here's a line-up of some of the colors I use.
The top line is for dirty water, my favorite for real dirty water is the chartruse clown.
The next line is for medium water, the so called "steelhead green" water color. I'll use these colors in the green colored water down to clear and up to dirty, adjusting by size accordingly.
The last line is my clear water colors. Many of the same as the green water colors, but maybe a little smaller in size.
I like to run something that gives some action like a spin-glo or birdie if I feel like I need to get the fishes attention a little more-like in dirty or cold water.
I like to try matalics when the sun is out.
A few more thoughts-
Match the hatch-
on one day I was going to fish a new river, we noticed that every corkie that was washed into an eddy was rocket red, it seamed that it was the only color people had been using. Guess what, the fish we hooked that day were on rocket red.
Sometimes a certain color will work well on a certain river because of water color, or that particular run of fish.
On another note.....
Change them up-
sometimes the fish get tired of seeing the same old thing. Give them a different color than what they've been pounded with.
I can tell this is the case when I've fished a peice of water for a while, we've caught a few fish out of it and I know there are more in there. Then I'll switch color and hook one on the first cast with the new color.
It's a good idea to use contrasting colors when you are adding yarn to your drift rig. It gives it a natural apperance and helps it to stand out.
Rainbow color combos or drift bobbers are another good idea as it will give you several color options in one so you can match whatever the fish want or the visibility of the water.