Responsible pet care includes
Ensuring your cat has been neutered / spayed. Apart from unwanted pregnancies, the cat is less likely to wander off if this procedure has been carried out.
Microchip the cat so it can be traced if it does goes wandering (or jump into a stationery vehicle for a ride). Remember if you move home, change the contact details on the microchip.
Keep vaccinations up to date, and a veterinary "MOT" once a year is no bad thing.
Consider pet insurance to even out the cost of non routine veterinary treatment.
Don't overfeed your cat, and encourage it to exercise by playing with toys etc.
Keep your fences in good order so as to reduce the risk of unwanted visitors coming into your garden and attacking your pet.
Remember that the sweet little kitten today, will grow and become a sweet big cat if it is happy and content,
According to the PDSA's statistics, a cat costs £17,000 over its lifetime.