When introducing a new cat to a household with existing cats, it is important to take it slow and be patient. Start by placing the new cat in a separate room and allowing them to explore the space and get used to the smells of the house. Once they are comfortable, gradually introduce the cats to each other by allowing them to sniff each other through a barrier. Make sure to provide plenty of treats, toys, and positive reinforcement. Make sure to also provide each cat with their own food, water, litter box, and bed. Finally, be sure to provide plenty of love and attention to all of your cats.