Bad idea in my opinion. However, MN has a department of commerce you can tap for various publications. You will probably want to set up an LLC (yet more expense) for lots of reasons.

Also check with the cities you plan to buy any rental in - they will have rules and regs to follow, and they are all different. When I looked into this way back when, I quickly came to the conclusion my life energy was worth more than the struggle dealing with just one bad renter would likely entail.

All that said, you can avoid most of this by hiring (yet more money) a professional rental company to manage the renters and units. But I'm not sure how this would impact your cash flow or profit (if any). Finding a good rental company is yet a different story...