First things first. Do you live in a house or apartment? If its a house and you have a humidifier attached to your furnace you cabn turn it up a bit for the entire house.

Cover 3/4 of the lid with press and seal plastic wrap (Grocery Store)
If you use newspaper you have to mist a few times a day. If you use cypress mulch you can dump a little water on it and it will stay moist for a few days.
Add a huge water bowl and put it close to the underfloor heating.
To keep the humidity up in my basement i bought a baby pool for 29 dollars at wallmart and stuck it in a corner. I top it off every couple of weeks. A powerhead and some freshwater plants keeps the water pretty clean.
This also keeps up the humidity in my whole house.