Training your cat to respect boundaries and use the litter tray are the very basic essentials you must do as soon as possible. I also believe it is important to train your cat to respond to their name. It will help increase your cat's intelligence and awareness as well as making it easier for you to do further training later on. And if your cat learns to respond to its name, you will have a much easier time getting it back inside when it does escape.
To have your cat recognize and respond to