Some breeds of cats require a lot more attention than others and particularly those cats that tend to live inside more often than other breeds that are happy to run around outside and keep themselves occupied. Cats with longer fur will tend to shed a lot more fur about the house which will require more cleaning and they will also require more grooming which means you will have to spend more time looking after them.
Cats are a lot more independent than dogs and are more difficult to train, and this is something that you need to realize and accept. If you like to travel a lot or you are away from the house a lot of the time, you will need to arrange some other person or service that can mind your cat and ensure that it gets fed and watered regularly.