You want your wood to smolder, not burn, so you want some residual moisture in it. If you look in the "what kind of wood do you use" section, you will see lots of posts on this topic. If memory recalls, I think around 20% moisture is considered ideal, although some have great results with big box store Very Dry wood. If you are given the choice, though, I'd recommend you use the naturally seasoned woods. Good luck.