It's a broad question. What kind of enclosure are you using? What kind of substrate?
I think most advocate a daily heavy misting and/or pretty much dumping water into the substrate. It really depends on the substrate being used though too. Whatever you do it may not be enough if your enclosure isn't enclosed.
You can make your own fogger quite easily. Just buy a good cool mist vaporizer. I love the Crane brand. Grab some vinyl tubing from Home Depot and attach.