Don't know if this was mentioned or not, but you can get bunch of crumpled paper towels, wet them and put them in the tank. I used that technique awhile ago and it works great. Just re-mist them every 2 days or so. That will up your humidity to 60+. Also try puting your water dish either directly above a UTH or under a lamp. That should increase it too. Finally misting the substrate helps too, but I don't like having my bp on damp substrate.