For STRs, focus on areas with robust tourism and flexible regulations.

Not every state or city mandates that any landlord has to accept Section 8, because the landlord has to not only subject their property to Section 8 inspections, rules and regulations, they also often have to separately arrange for the tenant to pay the non-covered part of the rent and can face difficulty evicting just based on that.

Narrow down your location based off of your comfortability, budget, local property owner regulations, and rent to price ratio, and you'll be building a portfolio in no time. 

If you're refinancing to a business purpose loan that's totally fine, but chances are good you'll need a lease in place for the unit you were occupying so the lender feels confident that it's strictly going to be used as an investment property.

Not following the requirements (within Seattle city limits will likely have additional rules and regulations) opens the seller up to liability.Additionally, the seller always has the option of offering "cash for keys" arrangement but be sure that no funds change hands until after the property is vacated and locks are changed.John

It is the worst because you need to understand the patchwork of regulations across the state, which can vary down to a neighborhood by neighborhood basis.

The final wild card is government regulation and how it could affect the investment.

I have been strictly renting to MTR tenants and have provided nothing more than a smart TV and internet access. 

And the numbers are pretty good on the projects I've looked at. these are the very recent regulation that's from what I read, it makes more sense to add ADU into small MF.

I didn't even think to check my local govt on the regulations about rental property.