There's a lot of variables in smoking and a ton of techniques. First of all I would say that trout is very different than coho and to do both at the same time in the same manner is a tough choice to pull off. How soon you plan on eating the stuff up plays a big part in the salting (brining) time as well. For a quick smoke-and-eat you can sprinkle rock salt and brown sugar directly on the fish and throw in the smoker. Knock off the rock salt when she comes out and your good to go......for trout I recommend this as it tends to dry out quickly, but it won't keep very long. For coho and steelhead you can use the same technique, but let the salt sit on the fillets overnight and then rinse thoroughly. Pat dry and dump the brown sugar on the fillets and let it melt and drip off..usually about two hours or so. Then throw in smoker and remove when firm to touch of finger. Will keep for about a week and half with refridgeration, and is excellent. You can baste with syrup while smoking if you want to try a little something different. I like this, but too much will cause dripping which may or may not be a problem, depending on your set up. I scrape off the drip tray mid way through the smoking process to keep the drippage from smoking too much.

Bottom line...experiment until you come up with something you like. I use alder exclusively any more and cut my own into chunks. It's free and smokes slowly and I like the flavor. I never add water to the wood...after all, you're trying to dry the fish.