Since I started my so-called writing career discussing this exact topic, here's an updated version to help keep both you and your cat happy regarding the litter box.
Suggestions to help keep your cat using the litter box (instead of the rest of your house) for a potty.
1) The Scoop on Litter
a) STYLE - Scoopable litter is probably the easiest type to keep clean. Scoopable litter forms clumps when your cat pees, which are scooped out with a litter box scoop/shovel. Stools are removed the same way. Find a litter brand that your cat likes and stick with that brand, no matter what is on sale. Switching brands can make a cat find another location to potty.
b) SMELL – Avoid scented litter, which can be irritating to the cat’s respiratory passages, especially in a covered litter box.
c) CLEANING RULES - The importance of DAILY scooping cannot be emphasized enough. A good comparison is a porta potty. Do you want to use the fresh, clean porta potty that still has a full hand sanitizer? Or the one that hasn’t been cleaned in a week, it’s hard to breathe inside, and there’s no toilet paper left? Keep your cat happy by removing all the pee and poop on a daily basis, so it is fresh and clean and smells good in the litter box. If the litter box stinks, it is because it is not being cleaned often enough.
d) MORE CLEANING RULES – Daily scooping isn’t enough. The whole box needs to be dumped and cleaned frequently (every 1-2 weeks). Clean the WHOLE box, top to bottom. Don’t use cleaners containing vinegar, which can smell like another cat’s urine and confuse the matter. Once the litter box is clean and dry, then add a new box of fresh cat litter—the same brand as before. Don’t change things up, because this can also send your cat seeking other locations to potty.
2) Location, location, location – Several rules to be followed
a) Make sure the location is easy access for your cat. You wouldn’t make your grandma go all the way downstairs to potty, so don’t make your elderly, fifteen-year-old cat travel downstairs every time he/she has to potty.
b) Make sure the location isn’t “scary.” For example, don’t put the litter box next to the noisy washing machine, dryer, or furnace which can kick on and frighten a cat simply trying to pee in peace and quiet
c) If you have multiple cats, provide multiple locations to potty. Having 3 litter boxes all in the same room doesn’t count. You need multiple locations, because sometimes one cat can bully the others away from the potty and cause potty accidents around the house, but that bully can’t guard litter boxes in multiple locations all at the same time. In addition, it is recommended to have one more litter box than the number of cats in the house (for example, two cats means three litter boxes).
3) Size is important– Cats come in different sizes, and so do litter boxes. If your cat is petite (under ten pounds), then the typical cat litter box size is probably fine. If your cat is of the more sturdy variety (say, 15# or more), then you need to size the litter box accordingly. Your cat should be able to fully stand up and turn around within the confines of the litter box. As a good comparison, think of the tiny bathrooms on airplanes—would you want to potty in them every day for your whole life? Probably not, so give your cat the same consideration.
But don't just search the Internet for litter box advice. Please ask your regular Veterinarian any questions you might have on the subject.