Scoop the litter box twice daily - at a minimum.
Use clumping litter or low dust litter - except for kittens younger than 8 weeks of age.
Use unscented litter.
Keep the litter deep enough 3-4 inches.
Use large litter boxes.
Have enough litter boxes available. One more than your cat household 3 cats = 4 litter boxes
Have litter boxes placed in a quiet area.
Use a litter mat that is comfortable for your cat to walk on.
Seek veterinary attention if your cat stops using the litter box.
Use pelleted (pine or newspaper) or crystal/white pearl litters.
Use scented litters or any deodorizers.
Use plastic 'grass' mats.
Punish your cat for not using the litter box.
Put your child(ren) in charge of litter box maintenance with adult supervison.
When cleaning your litterbox:
Scoop litter boxes at least twice daily removing both feces and urine.
It is critical to be able to remove both the feces and the urine each time the box is cleaned. Clumping litter is helpful for cleaning that allows for this to be done completely. Higher quaility litter is a must, to assit in keeping the box clean.
EXCEPTION TO ABOVE: Clumping Litter and Kittens (younger than 8 weeks of age) often have temporary bouts of diarrhea for various reasons. They are also more apt to step in their feces and then end up with messy cement boots. Very small kittens may even attempt to eat the litter. For this reason, I advise using a NONclumping litter for small kittens.