If the goal is to open a commercial school, but you want to start small, I think that JowGaWolf is right - start by subletting in a community or someone else's commercial space, rather than by teaching in your house. If you teach at the rec center (or at a gym, dance school, etc), there will be good parking, public restrooms and possibly changing facilities, and you may have access to mats or other exercise equipment rather than having to buy everything yourself. Plus, if you teach at a rec center, they may advertise your classes to community members at little or no cost to you.