Advice on expanding my portfolio?

[Bryan Crow]

I have 4 paid-for SFRs with solid tenants in FL. All are managed by a property manager. I am ready to expand the portfolio with leverage. I have a full time job. Given my age (53), I do not want to put the business at significant risk. Therefore, I am thinking that a reasonable way to expand with minimal risk is to refinance one of the properties, using the proceeds as 20% down payments on 2 more properties leaving cash for refurbish. The properties I buy are $80k- $100k 3/2s in decent neighborhoods. 

My goal is to have 8 paid for properties in 10 years. 

1.What are the risks to this strategy?

2. Is there a better way to accomplish my goal?

Thanks in advance,

Bryan