I have a nearly 4 year old neutered female cat. I have been thinking about adopting another cat, but I fear they won't get along. Current cat is not really social, rarely likes being touched, instead requires attention: playtime, being near (but far enough), etc.
What are your experiences with second cats? Are there age / gender combinations which are the safest?
Edit: thanks for all the replies! Forgot to mention that she is an indoor cat.
As soon as you know that the first cat will only stay within the apartment, it is best to have two and make sure that they understand each other and do not fight.
But of course it is never too late. Above all, you should be able to reach the previous owner at any time. That you can return the second one at any time if they don't get along. The back and forth may be stressful for a short time, but it's better if they don't get along. Since you have a cat, I would also tend towards a tomcat (they like to cuddle more than cats) but sterilize if you don't want any offspring.
Edit: btw with returning i talk about 1-~15 days