I find Michigan to be a very interesting place to invest due to the extreme highs and lows in home prices in such close proximity. My advice would be to find a real estate agent that focuses on rental properties or even better one that owns rentals themselves. This agent would likely know the best places to invest in the area and where the sweet spots are where properties are cheap but up in up and coming areas.
I have found in my research that many areas are already overpriced and would be harder to make a profit from renters, but they are out there. Royal Oak is an area that I think is too expensive, but there are other places like Lansing and Grand Rapids where cash flow seems better.
Last piece of advice would be to check the laws for each city concerning rental laws. I'm no expert in this area but I have heard certain cities are very renter friendly and this can cause challenges for landlords if disputes arise.