Brrrr method opinions?

[Chris C.]

I'm a new investor but currently own four houses clear 3 are rented 1 is being repaired then my house I currently live in I owe 40% of the appraised value in which that was the one I was thinking of using the brrrr method on ,

      I have paid cash for the previous four so have to wait a while in-between but always liked the idea that if they were empty I wouldn't be making extra mortgage payments but more I read I realize I've been doing this wrong by having all my money in the properties instead of being able to purchase more 

So was wondering if the brrrr method would work good to help or maybe HELOC? Or other options?