It's paper.

@Chukwudi Motanya if you have the ability to go fannie/freddie for your investments, you'll definitely get better interest rates and less (or sometimes no) fees. fannie/freddie cap out at 10 financed properties, though, and they will qualify you based on income and ability to repay. still, this is the best option for your first 10 if you have the income on-paper, but yes, you would be paying on 10 different mortgages one at a time. 

@ Grant RothenburgerGood point but I'm pretty sure they're talking about buying a piece of paper that says 'whatever'.

@Beau Pearson It sounds like an excellent idea on paper but I've tried this before and I'm not a fan.

For my SDIRA, I write paper and do equity participation deals with flippers. 

Gaining some insight from a Memphian with knowledge of the industry and to hear about your personal experiences in residential real estate would be incredibly helpful for my research paper.

While I'm sure some people like explaining deals over the phone, personally I'd rather send/receive them in my email so I can look at the numbers on paper.

Three months after closing the interpreter approaches my client with a piece of paper and told him he needed to sign it in order for hm to obtain financing for a home. 

You have a lot more flexibility on location and terms, with say $5,000 when you invest in paper.

About five minutes before sale, you see some old guy (At least usually in my area) with a clipboard full of papers.