To have the same humidity throughout the room, place the humidifier in the middle of the room. Avoid installing it near the wall.
In order to ensure adequate air flow, open the door to the room. By doing this, you avoid moisture build up and mold growth. Run the humidifier whenever you are in the room.
Once every few days, clean the humidifier to remove bacteria and prevent mold. Read the manufacturer's directions for specific cleaning instructions.