Here are a couple tips to help you care for your cats litter box. Place the litter box in a low "people traffic" area, so that your cat will be more likely to use it. Litter boxes placed in high traffic noisy areas are unappealing to cats.
Have one more box than the number of cats in the house. If you have two cats, you should have 3 litter boxes. If you have 5 cats, you should have 6 litter boxes.
Scoop and remove soiled litter daily. A clean box is appealing to cats.
Thoroughly clean the litter box about every 2 weeks. Don't use harsh chemicals. Scrub the box with a mild dish soap and scrub. Rinse well with water. Cat's will often be repelled by the odor of harsh chemicals.
For more information, please read is excellent and complete article on litter box care. go to: The Fine Art of Litter Box Care.