Wouldn’t it be really great if we could just bring home a new pet and they would instantly love each other and get along? Sometimes that isn’t the case, especially with cats. The new cat introduction process doesn’t have to be as much of a nightmare as some believe. Below are a few tips in helping the newcomer feel more at home with your existing resident cat.

Slow and steady wins the race. Forcing both cats on each other from the “get go” isn’t a wise decision. To avoid excessive aggression, experts advise to introduce the two cats gradually. Have a separate area for each cat to eat and sleep in with a closed door. Be sure to spend quiet time alone with your new cat while she is confined to her new space. Of course, pay extra attention to your resident cat during this time of transition as well.
Curiosity doesn’t always have to kill the cat. Both cats will realize there is a possible new friend on the other side of the door and will become accustomed to their sounds and smell.

Not all cats are the same. Just like humans, they each have a very different personality and some are more quiet and alone, while others are social butterflies. Do not expect your resident quiet cat to immediately start playing with the newcomer. A resident quiet cat who has never shared space with another animal may be a less inclined to share her space with a new cat.
Swap smells. Cats have a very keen sense of smell and associate it with people as well as other animals. After a few days, switch blankets, toys etc of each cat with the other. They will begin to associate a particular smell with the other animal. The face to face meeting will go more smoothly if each cat has a scent they are already familiar with.

After a few days of isolation, the new cat should be ready for a face to face meeting with the resident cat. With the resident cat in isolation in another part of the home, casually open the door. Let the newcomer cat walk around the house, browsing and smelling, stopping where she may want to.
This is all part of the process of her getting used to her new home and its smells.
When she has had ample time to walk around her surroundings, open the door to the resident cats room. Be sure to be present when the initial introduction takes place as either cat may become aggressive.
Either cat may just look at the other, sniff a bit, and walk away. Do not be alarmed if when both cats first meet, you hear hissing and yowling. Both reactions are normal.

If either cat should become aggressive during the meeting, DO NOT place your hands in between them, or try to grab one to cease the fighting. This is very dangerous and you could become hurt. Clap your heads, yell, hit a spoon to a pot, but do not ever break up a cat fight. 
If the meeting doesn’t go as well as you had planned, try again another day with the basic steps outlined above. It can be a slow process, but when done right, eventually, your two cats can become best buddies and  live together in peace and harmony for years to come.