The best thing that works for me is water ionizer with a little air pressure:

water ionizer(fogger, mister, whatever)
rubbermaid resevoir(i think it's a 2.5 gallon)

all you have to do, is drill 3 holes in the lid. One for the ionizer's power, one for a 1/4th inch air supply hose, and one for a 1/2 inch tube connected to a propogation tent.
I have my fogger run 15 minutes, every hour and a half. This keeps the environment very humid. I keep the air pressure on the whole time, so they have a "little" breeze running through while they're not being fogged. I have my 1/2 inch tube connected to a 2 way splitter, one hose going into one tent, and another for my other tent. I also keep a heat mat under both tents.