@Celine Li Recommend you first figure out the property Class you want to invest in, THEN figure out the corresponding location to invest in.Property Class will typically dictate the Class of tenant you get, which greatly IMPACTS rental income stability and property maintenance/damage by tenants.If you apply Class A assumptions to a Class B or C purchase, your expectations won’t be met and it may be a financial disaster.If you buy/renovate a property in Class D area to Class A standards, what quality of tenant will you get?

For example, if I want to install new plumbing in the bathroom because the old one is old and broken, would I need a permit to do these fixes? 

We expect to make 3-4X our invested capital.

After you paid for a hotel for your tenants for the last week while the ac, the heat or the water heater was broken.  

Seems like that has a bigger difference than you'd expect. 

Based on your question and your expectations, stay in index funds.

And be sure you have the ability to fire them at will and settle up so if they aren't progressing how you would expect, you can move on without paying huge penalties or in some cases not having any way of being able to fire them at all (some of the builders' contracts are ridiculously in their favor). 

Take care of any reasonable property related issues quickly and expect your tenant(s) to take care of their responsibilities quickly also. 

Even if it’s only $25 (Minimum 1-2%) it’s expected.

Honestly, most people don’t expect it anymore unless you're catering to older guests or sports fans.