This is an excellent question and, if you are reading this I love that you are asking about this subject! That is what we at Pawtology have dedicate our whole lives to; teaching you how to take care of your senior pets. Take a look around our site and follow our blogs and podcast and you will get a lot of amazing information.
But, to answer your question, taking care of a senior cat isn’t all that different than taking care of a younger cat. To me, the importance of regular vet care becomes much more necessary for senior cats because the signs and symptoms of diseases can be very subtle. The quicker you catch something, the easier it is to treat and the better your cat will do. Beyond that, everything else stays the same: food, water, litter box, toys, exercise, etc. You will just need to adapt these to the unique things that happens as cats age.
– Dr. B