Paying off a property

[Justin K.]

Hi BP, 

I'm finally closing on our first property. Now I'm starting to think about what to do in the future for more properties. I am wondering what method people on here use as far as acquiring credit for multiple properties: Have you paid off your first property and use it as collateral, or just open multiple mortgages in other ways? What are the merits to the different scenario? 
My train of thought is to pay off the initial property quickly and use that asset as a means to secure future loans. As a new investor, I'm sure that I'm overlooking something, and of course having so much cash in one asset could be a con. 

Thanks for any wisdom,
Justin