The best way to pet a cat is to ask first. You just hold your hand out at face level so they can come do a little sniff, and if they want to be touched they will communicate it through body language. Some cats will push their face into your hand somehow, or do a little head boop. One of mine does this adorable little move where she turns her head and pushes her neck towards your hand. If they don’t want to be pet they will usually back away or show they aren’t comfortable in some other way ranging from disinterest to aggression. The best way to treat a cat that doesn’t want to be pet is to ignore it. They see that as warm friendly behavior. In the end some cats may just never be interested, and that’s ok, because they are all their own special little creatures with their own thoughts and feelings.