Cats prefer to relieve themselves in a peaceful location without a lot of action or loud noises in the background. However, cats also do not like having a litter box that is too far out of the way.  Make sure your cat can physically access his litter box. Do not put the box on a high shelf or an otherwise difficult to reach area if your cat is old and has trouble jumping or climbing. Avoid noisy or high-traffic areas. Do not place a litter box next to a washing machine, for example, or in a crowded hallway that gets a lot of foot traffic. Cats want peace and privacy, but they also want convenience.  Do not put your cat's litter box in close proximity to its food and water dishes. This may discourage your cat from using the litter box. You may also want to place your cat in his box shortly after he wakes up and after playing, as all of these are times most cats will want to excrete wastes. Putting your cat into the litter box during times he will likely need to relieve himself, such as after eating a meal or when he's just woken up, may help remind him to use the litter box every time he needs to go. Cats will not want to use a litter box if it is dirty, and may resort to urinating or defecating around the house.  Wear rubber gloves while handling cat feces to reduce the risk of contracting toxoplasmosis.  Scoop out solid waste and clumps of urine-soaked litter everyday. Wash your hands thoroughly after handling soiled cat litter, even if you wore gloves.  Do a thorough cleaning once a week. This entails dumping out old litter, washing the litter box with a mild detergent, thoroughly rinsing the soap away, drying the box completely, and pouring in a fresh layer of litter. You should only add about two to three inches (five to seven centimeters) of litter when refilling the box. There are many different types of cat litter, made from a variety of different materials. The most important factor is finding a litter that your cat will want to use. Most cats prefer clumping, unscented litter. However, your cat may...

TL;DR in Vietnamese:
Đặt khay vệ sinh ở nơi yên tĩnh. Đặt mèo vào trong khay vệ sinh ngay sau bữa ăn. Dọn sạch khay vệ sinh. Dùng loại đất vệ sinh mà mèo ưa thích. Thưởng cho mèo vì hành động sử dụng khay vệ sinh. Không nên phạt mèo vì sự cố đi bậy ngoài khay vệ sinh. Áp dụng hình thức huấn luyện giam cầm như là biện pháp cuối cùng.