Using Rental Income+Equity to purchase 2nd Rental

Greetings. 

I am trying to wrap my mind around the potential tax benefits, deprecation, and cash out opportunities of a fully owned property with the intent of reinvesting into another property and increasing cash-flow.  

Fully owned multi-family: 

Value                       $315,000.00

Rental Income           $28,680.00

Prop Tax                      $2,160.00

Insurance                     $2,400.00

Repairs  @ 2%                $573.60

Income Tax                  $8,604.00 (I currently set aside 30% of rental income)

This is where my questions start:  I want to cash-out the equity in the property to reinvest. My understanding is that I can either

1. Use 75% of rental income, and pull out 20% for a downpayment on another property

or 

2. Take 80% of current property value for the purchase. 

I don't want to overextend myself so I'm trying to see what the pros and cons are with these option (or any other ones that you might have) and what my financial limits are in considering other properties. 

Any thoughts, help and personal experiences are welcome and appreciated. 

Thanks