Cats are neat by nature, which increases success of housebreaking. Even kittens learn this instinct early in development. Most problems with litter box training come from improper substances in the litterbox or improper placement of the box. To avoid development of bad habits, fix any of these problems early in training.
Litter Box Training a Kitten
Start litter box training your kitten as soon as you bring him home. Start by keeping your kitten confined to a smaller area with a litter box that is easily accessible. Kittens won't travel far to relieve themselves, so the box needs to be conveniently located as well as low enough that the kitten can get easily in and out.
Stimulate the kitten's interest in the litter box by moving it a little so the kitten will chase and scratch at it. Don't scare the kitten, just slowly move it to increase curiosity.
Keep a schedule of when the kitten needs to relieve himself so you can encourage him to do so in the box. Feed regularly and play with the kitten before and after the meal to speed up the process. Reward the kitten for going in the correct space with a treat or game.
Gradually allow the kitten more freedom, but keep the litter box in a similar location for at least a few months, if not permanently, as the kitten adjusts.
Litter Box Location
To litter box train a cat, use the similar methods but focus more on the aesthetics of the litter box. Initially, keep the cat in one room with a conveniently placed litter box.
There should be one litter box per cat in the home to prevent competition, especially for the new cat. Place the litter boxes in quiet locations that allow the cat privacy. Avoid proximity to loud appliances or anything that might scare the cat and teach an aversion to the litter box.
As with the kitten, be sure to generate interest in the litter box and reward for compliance.
Appropriate Litter
Just as a kitten needs a litter box appropriate to its size, so does a cat. If the box is too small, the cat may start to go outside the box. It also needs to contain appropriate litter. Cats find certain smells very aversive, so deodorizers in cat litter are often a turnoff. Use scentless litter for the best results. Put enough litter in the box for the cat to easily bury its stool.
Clean litter boxes daily. If a litter box is too messy, a finicky cat will not want to use it and may start to go elsewhere, initiating habits that will continue even after the litter box is clean. Add a layer of fresh litter daily as well. The box should be emptied and cleaned once a week.
Housebreaking cats and kittens is easier than training dogs since cats are extremely clean by nature. However, if the litter box area isn't clean enough or is located in a scary or aversive environment, they may develop bad habits that will be much harder to break. Paying special attention to your cat's litter box is the best way to ensure training success.