I'm heading in this same direction. Get certified as an instructor, if you aren't already. Get some liability insurance. The NRA has great instructor policies at a great rate. You just have to be a NRA member to take advantage of them. I looked into private insurance through my regular insurance agent's company as he's a broker for many companies. Don't bother. Use the NRA sources. They advertise rates through their web site. As stated, look into Michigan's laws that might affect you. You will have to find a range that will let you use it for live fire exercises if you don't have enough private property to use, if your laws permit it. Just doing classroom won't cut it. Then, there's the business aspects you will have to deal with. Basically, you will be running a small business. The tax breaks are pretty decent, but you'll have to research the laws in your municipality to having such a business and what is involved. There is much more involved than you may realize.
Feel free to contact me directly if I can be of help.