Best way to Borrow against a rental?

I have a 8 unit multi family property.

1 single family home

2 duplexes

3 mobile homes all on 2.5 acres of land.

Grosses $6500 a month.

I own the property free and clear. I’ve had it for almost 3 years. Excellent rent history, rarely a vacancy. I would estimate its value at $500,000.

My question is what is the best way, and easiest way to borrow money against this property? I am needing the capital to help expand another business that I own that is exploding. Thanks in advance!