When to add to your buy and hold portfolio

[Malcolm Kelly]

Hello everyone,

Im new to Bigger Pockets.com so this question may seem elementary to some but Im curious. Im in the process of selling off a previous business venture and once I do Im going to use the money to strictly invest in buy and hold properties in the Houston area mostly multi units. 

My question is once you've purchased your first rental property how do you determine when its time to add the next property to your portfolio? Is it positive cash flow? A certain length of time with positive cash flow? ROI? Im assuming there has to be a rule to abide by in the building of your rental portfolio. By the way the podcast are priceless.

Thanks for any help.

Malcolm