Going in, telling owners your experience and education on coaching. Showing them your skills in running a class. Proving to them that you have your Level One Certification and that you are able to preform the movement and can demo and teach. They will likely ask you to do a mock class, where you run the class as you would on your own and for them to see how you do. They may also show you for awhile/ weeks how they run the gym and have you shadow some classes and teach you some how to coach if you do not have experience.