I know I've read on here that some areas are better for renting and some are better for fix and flips. How do you know which your area is better for? I guess ask an agent. Otherwise, I don't know. Perhaps researching to see if there are a lot of fixer uppers on the market in that area. If almost everything is move-in ready, then maybe finding a fixer upper is good. But if you're looking at buy and hold in an area with no other renters, maybe that's not a good idea? Keep in mind, by "area," I'm talking about neighborhoods, not whole cities.
I just recently decided to branch out from my city I normally invest in so that I could have some geographical diversity. So, I can tell you exactly what I looked at when deciding where to go next. Here's an article that might help as well.
https://www.biggerpockets.com/renewsblog/cities-re...
I read that you shouldn't invest in a city that you don't want to go back to visit at least annually to check on the property. I also wanted a city with more than one draw, like a town that's got both a military base and a college or it's known for it's tech and is also the county seat or state capital. Personally, I wanted something at least 60k people strong as I felt like it would be easier to find renters, but I've seen plenty of threads on here where people are doing well with rentals in much smaller markets.
I went to Sperling's Best Places to Live site and looked up cities I was interested in. I looked up the median price of a home (which knocked out some otherwise perfect cities), crime rates (just my personal preference--but lots of folks live there, so maybe it doesn't matter), size of the city, and housing stats (I wanted at least 40% of the population being renters with less than 10% vacancies).
I also went to their Wikipedia page for final decisions. Another thing I suggest is to put that city name in here as a keyword alert on your profile so you know when people area talking about it and look for any forums specifically for that city. I've learned a lot through threads and city-specific forums on here. Just last night I was reading about how my chosen city has a very strong market and some houses actually sell for above the asking price and almost none for far below. I know that just offering on MLS houses might not get me the numbers I want, so I'll have to use other ideas to find properties (like driving for dollars or calling landlords on Craigslist to see if they want to sell).
As for what happens if no one buys/rents, while I realize my opinion isn't prevalent on here, I don't buy anything I can't afford to pay for if no one wants to live there. My risk tolerance isn't super high and I couldn't sleep at night if I was leveraged like some folks on here. lol I also don't buy anything where I wouldn't want to live. (I feel like that makes it more rentable.) But then there are LOTS of folks who make a living at just Class-C rentals, so don't take my opinion as Gospel. lol
Good luck!