Once you find a house that you believe would be a good rental, meaning desirable to your target market of customers (people within a couple of mile radius of the place), and all of the costs of monthly ownership that you can accurately project fall below the rental amounts that you project that you can get from your target customers, then you have a possible business asset that you can use to produce income, and have renters pay down the mortgage, while hopefully it goes up in value at least with the rest of the economy. 

Legal documents and customs are tricky in a native language let alone a foreign one.

The cost of labor and materials now is insane.The type of work on my custom house is about 400 a foot.

If you want to run a charity by all means run a charity but don't speak such insanity that letting customers STEAL is ok, it's not.

The best indicator is whether the city has significant and sustained population growth.

I focus a huge amount of time on tenant screening and providing exceptional property management/customer service.

An AC unit in beaucoup Hot weather may have an up charge from the installer because he knows he can get it from customers who want immediate cooling.

Personally, I find that buying is usually quicker and cheaper upfront, while building offers customization but requires more time and coordination.

For example, if a family is displaced due to extensive water damage that will take a few months to repair, the insurance company will then look to find temporary housing for their customer/displaced family.

Seek longevity, sustainable not extreme volatility.