I've tried many methods to get humidity up - even combinations of several methods. In hindsight it seems the easiest (sometimes cheapest) things to do (alone or together)are:
1. Just add a humid hide (tupperware dish with an access hole cut in the lid or side filled with damp spaghum moss) to the warm side (if your BP uses it then he's keeping his own humidity up). But mine won't use one, so.....
2. Cover the top with duct tape (on the top outside of the screen top-never put any tape inside the tank). Just leave openings for any lights you have on top. If you don't have any lights on top just be sure to leave a bit of ventilation. I've found some nice black duct tape at the hardware store - looks much nicer than the standard grey.
3. Cover with damp towels. You can do this in addition to or instead of the duct tape. You can always find nice small black towels that look better than say a sponge bob towel. 
4. Try a humidity loving substrate such as the compressed coconut bricks (Bed-a-Beast, EcoEarth, etc). They can be a bit of a pain to prepare them, but well worth it. It looks natural (kind of like the forest floor), easy to spot clean and helps with humidity. You can even feed on it and it's environmentally friendly. 
Of course there's misting....but that can be down with any of the above suggestions or just nix it - it is such a pain to me. You can always switch to a rubbermaid setup, but if you're going for a nice display cage that kind of defeats the purpose (although rubbermaid setups can look real nice too). There are other more costly methods, but I've found these ideas to be the ones that work the best. Maybe try one, see how it works and add other ideas as needed. You'll find what works best for what you need and maybe find new ways.
Hope this helps! Glass tanks can be more work for a BP but it's worth it for a nice display tank.

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