I'm still learning about this too. In a 30 gal breeder (glass tank), I've used newspaper (had to adjust heat WAY down), and varying levels of cypress, aspen, or a combo of both. The cypress stays too moist, and the mixture of aspen seems to be working well, but I have the temp/humidity gauge in the tank constantly. I have an UTH on one side, turn a lamp on during the day for extra warmth, and seem to be constantly adjusting the rheostat (it's a fairly new set-up, in a new room...the old 30 gal did well once the bedding was in and everything was settled for a while).
My next step is to enclose the breeder top a bit, since the screen is likely letting the A/C in/heat out more than I'd like.