[mesmark]

I'd suggest looking into a textbook. You could continue to do other parts of the class based around your student's interests, but with the textbook you wouldn't be required to create every part of the curriculum and make sure you were building and moving in a upward direction. Making all your own lessons, start to finish, isn't hard at first but after a year or so of that you may find it more difficult. Most textbooks have a balanced approach and there's still a lot of freedom for expanding beyond the textbook and practicing certain grammar points and vocabulary.