How I can fast my rental investing pace in my situation?

[Michael Luo]

I am a beginner of real estate investment. First time to be here. Does someone have any suggestion for my situation? I brought 2 stories house in 2007 around 200k and paid off the mortgage in 2017. Because the job changed, sold my first property for 300k. I used 100k as DP to purchase a house as primary (with mortgage) and use 200k to buy my first rental property (no mortgage). In 2020 brought my 2nd rental (with mortgage). Using the cash flow, I should be able to buy a rental for every two years. I am reaching 60 years old. How can I increase my real estate investing pace? like some of you guys buy two or three rentals every year or each month.