How to choose a compatible cat
A cat closer in age to yours may be a better match than one that’s much younger or much older. Young cats do better with a playmate close to their own age. They will get frustrated with a senior cat who prefers napping to playing. Conversely, a senior cat may not appreciate a young cat or kitten disrupting his/her golden years.
If your cat is:
Timid – he/she would probably prefer to be with a calm and relaxed cat.
Dominant – he/she would probably prefer to be with a confident yet calm cat.
Very loving/sociable – he/she should be fine with a cat from either end of the personality spectrum.
Size can make a difference, especially if you have a dominant cat. It is often said that cats of similar size and build will accept each other more quickly. Try to choose a cat who is the same size or slightly smaller than your cat.
Male (neutered) cats are believed to be more accepting of other cats, both male and female. Female cats may not get along as well with each other.