Consider two Kitties instead of one

In my lifetime of experience, I have seen that most cats do better with a friend-another cat. Cats are social animals. In the wild, both the large cats like lions, and the feral domestic cats all live in groups. Cats that live alone can develop pyschological problems from the loneliness and boredom, especially if the cat must be alone for several hours a day while the family is at work and school. When you are ready to get a kitten, bring home two instead, the added cost is negligible compared to the rewards.

Introducing new pets to home

Introducing a new cat to a home that already has cats can be frustrating. Cats are territorial, and even though you brought the new cat in, it is still trespassing.
To ease the initial tension of introduction, rub all of the cats in the home, both new and old, with a talcum or baby powder. This will mask all of their scents which is how cats mark their territory. Since all of the cats will smell alike, they won´t feel the need to defend their territory from a stranger.

Stopping Fights Between Your Cats

Cat Behavior Problems - The occasional cat fight is expected in multiple cat households, because cats are territorial. However, when aggressive behavior becomes the norm, you can take steps to stop it.

These are some cat training tips I use, and a few more from Friskies cat food: Identify the aggressor and victim, then separate the cats when they can´t be supervised. Give the aggressor corrective measures, and the victim rewards.

Corrective measures can include: confinement in a less attractive space; place a collar and bell on the aggressor; squirt the aggressor with a water sprayer during agressive acts.

For the victim give rewards such as free roam of the house, plus edible and affection rewards.

Gradually increase the supervised interaction, rewarding good behavior and using corrective measures against cat agression.

Sand Boxes-More than one?

It is best to have at least one sandbox per cat in your house. Some experts recommend two boxes per cat, but with constant cleaning that isn´t really necessary. I do reccommend scoopable litter for multi-cat households to make the cleanup easier, and less expensive.

Lessen the defensive posturing

To help lessen the defensive posturing between housemates, take steps to make the cats smell similar to each other.
Rub talcum powder on each cat or spritz cologne on your hands and when it is dry pet both cats (don´t put the cologne directly on the cat-their noses are much more sensitive than humans). You should use the same grooming tools (combs, brushes, towels, mits) on both cats to transfer their scents to one another.