Tennessee Firearm Instructor Law?

I want to start a small part time business instructing people on the use of firearms, particularly handguns. I know you must attend an NRA Instructor Course or its equivalent, and submit it to the state to be state certified and to teach in a school. But, if I am only teaching people one on one outside of any school, do I have to attend the course and be registered with the state, or can I simply go about running my business as I see fit? Thanks in advance