How to acquire more rental properties

[Mike Cicchino]

I want to see if anyone could give me advice of getting loans for future rental properties. I currently own 2 rentals that are paid off and I finance my own house. I would like to increase the amount of income properties I have, I'm just unsure of the options available to me. Or, which option would be my best bet. This is what I am concidering.

 taking out a loan and useing my paid off homes as collateral. And using that loan as down payments for a few other homes. 

Let's just say my loan will be for 100k. I would use 20k for downpayments on 4 homes on homes being sold for a price of100k or less. The extra 20k will be in reserve (for just incase)

Is this even a valid idea/option??

 I am in pretty good financial position but I don't know how people do it...I see a lot of posts about people getting new properties every couple months and I'm wondering how this works with the banks. I assume not everyone has enough money to make all these purchases with cash.