Traveled with two cats for years. Some things you need/should do.
Get the cat micro chipped. If it gets out your chances of getting him/her back are much better.
Always carry the cats rabies certificate. A health certificate from your vet makes crossing borders easier.
A good fitting harness and leash. A harness is much more secure than a collar.
A good crate. Our cats preferred to travel next to the bed, but we always carried a crate just in case.
Start with short trips to get them use to traveling. Our male cat was a terrible traveler at first. Our vet recommended we give him Baby Benadryl to calm him down. After a few trip he became a better traveler than the female. He would spend the day on the dashboard, just watching the traffic go by.
With some prior planning and practice you will enjoy your travels much better having your fur buddy with you.