What's the highest success percentage method to find a previous tenant's new address for this? 

And while nothing is foolproof the most consistent method of finding good vendors is relying on OTHER real estate investors that have worked with those vendors. 

The real skill is understanding the variability and risk in each number which is not always numerical or scientific.

I want this to be acceptable long term if I keep this method of financing. 

What are the best methods to independently verify zoning and land use data to ensure compliance with local regulations?

There are numerous reasons why they usually do not make good rent properties. 

What are the best sources or methods you use to accurately set rental rates in your area?

(G) Acceptable forms of payment of Rent (including Additional Rent) are ___ personal check, ___ cashier’s check, ___ bank check, ___ money order, and ___ the following online/ACH payment methods ____________________.

The investor “gave up” after numerous attempts to sell the lot or get a “refund” from the county proved unsuccessful.  

Are there any methods you want to stick with?