I keep my humidity between 40 and 60, usually aiming for 45 to 50 except during shed, in which case I would raise it a bit more. The size and location of the water dish, misting, covering, all affect humidity. to increase humidity: put a larger water dish on the hot side and cover part of the top with something to maintain the humidity, to reduce humidity: place a smaller water dish on the cold side, maintain as much air circulation as possible, and a heat lamp will help.