The reason you are reluctant to jump in is hardwired into you, self preservation, common sense, you actually recognize you're not ready to jump in with a good grasp of knowledge to risk your money.

Begin thinking:  As an owner, I have the right to rent, sell, paint, abuse and even burn any thing I own (yeah,  property would need to be owned free and clear).if I own it, I can manage it.Any law contrary would be an abuse of common sense and we might see another Tea Party :grin::Thinking no longer required{ yes, that's snide, satirical & couldn't resist :sigh: }

Is this common practice for Seller not to release rent roll until a contract is signed?  

Does it just comes with trial and error with this being your 24th property?

Is it very common to find deals in Louisville where the numbers work like Brandon Turner says they should?

Is this common for investors to do?

The most common example is when the landlord sends the renter’s application information to a third party screening company who then pulls the credit data.

I don't think it's particularly common to do so.  

I'm pretty familiar with the common ones posted here: "Driving for bucks", direct mail, for sale by owner, Craigslist. 

Scripts are a set of standard answers to many of the common questions people ask.