looking for direction in building my protfolio

[Mickey Harrison]

Some info:
I currently own

1. Primary residence (has a efficiency attached which helps pay 1/3 of expense;mor,tax,in) owe 126k 27yfixed worth 165k

2. duplex with 70k 25yfixed mor (through SBA). worth about 130k
-This property when full rented has a positive cash-flow of 6k yearly and breaks even if only one unit is rented. CURRENTLY RENTED TENANTS PRESENT FOR 3 YRS.

3. Single Family Home 50k 15fixed. worth 63k
- positive cash-flow of 6k a year. purchased a few months ago CURRENTLY RENTED TENANTS PRESENT FOR 3 YRS. Tenant is enrolled in sec 8.

I do all management and repairs (except major ie elec, roof hvac). To purchase my second rental investment I used the positive cash-flow from my first property for a down payment. Now looking to build my portfolio. I was looking for some suggestions on strategy.

Is it recommended to:

1.Repeat the same? Take the positive cash-flow from both properties and purchase the next property with a mortgage.

2.Pay down my lowest mortgage ASAP.

3.Max borrowed loans from FHA of 4 and then start paying down.

4.Save more of the cash-flow to do the next deal all cash.

5.Combine cash-flow and Home Equity Loan to do all cash purchase (will a HEL be easy even though all properties have a 1st mortgage.

All of the above would be done after I have at least 6 months of mortgage payments in reserves (not including primary res)

With interest rates so low, what would some of you suggest. I understand there are lots of variables just looking for a pointed direction to finite my plan.