I do somewhat agree with Brad that ensuring ample drinking water is key, especially if you're humdity is low. I dont agree that 30% on a regular basis is fine. Id be concerned about shedding.
Personally, I wouldnt want my
panthers to experience humidity below 35% for very long or very often. I wouldnt want
ME to experience humidity at 30% or lower very often either! Hurts my skin! I prefer 40% for me, and for the chameleons 40% as the low and 90% during mistings. Most of the time my cages are around 45%.
Ok I have two live plants in the tank a warm mist humidifier in the room and I mist three to five times a day and the humidity always drops to 35% or below some one please give us many suggestions.....its an all screen enclosure.... I'm thinking about buying a cool mist humidifier and pumping it directly in the cage for an hour three times a day....but then again it'll drp to 35% or below and I'm not finding this healthy or fun for my veiled cham.
Here are some ways to increase humidity that might help the OP:
Buy a second, quality digital hygrometer humidity gauge. Maybe what yours is reading is off.
Keep your cham in a smaller room, so that the humidifier you already have is able to keep up with the demand.
Dont use a screen cage, or use solid surfaces on three sides, to help retain moisture from plants and misting longer.
More frequent misting, maybe with an automated system. You dont want damp and standing water all the time - branches should dry between mistings. Doesnt seem like thats a problem for the OP.
Put more live plants in the same room, near the cage.
Keep fish or hermit crabs or anything else that lives in a tank of dampness nearby.
Put a bowl of water, with a sponge sticking up in the middle (half in water, half in air), near the cage. Similar to having an aquarium, the water will evaporate into the air. This really only helps if the room is smallish.
There are humidity humidistat systems you can have added to your furance /ac system that can make the whole house a nicer humidity, keeping it around 40% (or 37 or 41, whatever you prefer). Note: You dont want your house 50% or higher on a regular basis, any more than you want it 20% or below. And the humidity of your house should be guided by the outside humidity and temp - too big a different between indoors and outdoors can lead to condensation, which you dont want.
Set up the cage in advance of getting the chameleon, and then water and heat the cage just as you plan to when you have a chameleon. Monitor the temp and humidity, make your adjustments, and then by the time you get the chameleon you'll know what you need to do. 
