My advice is to find a fitness center that will let you teach as part of their services. Your liability worries will typically be covered under their blanket liability coverage. Be fair warned, "teaching" martial arts can become a very disenchanting experience. And the density of schools are extremely high these days, in fact a dime a dozen. I have advised many over the years to not "go commercial (full time)" but to keep it small, simple, and at will. The few that did not heed my advise later told me they wished that they did. Not trying to be negative it's just a road that I traveled for a long time. Best of luck.