Put every dollar you earn into the HELOC until you need to use it to pay bills.

If you find something close to where you live and reduce that management fee you can make more money.  

NET of *all* expenses, management fee, maintenance, future maintenance - I think it's a realistic 3.5% yearly return and it seems like there is not a shortage of tenants, and rents have indeed risen.3.5% is certainly not my goal in life....but I figured this is better than 1.5% that cash earns in low-risk accounts, so why not 3.5% in a low risk house.  

Break down the returns you have earned from your current properties and be able to talk about them/increase them over the years.

These type of properties are management intense, so you earn your cash flow.

To earn that hands-on learning offer to do some of the work that would be more tedious to that investor but can also help you learn in the process, such as drafting an offer letter, initial cleaning of the property, etc.When it comes time that you'll have the cash and debt (and credit rating) position for your own first investment, you'll also have a solid foundation of learning. 

Triplexes are going to be harder to find but I’m of the mind that you should go as big and expensive as possible since debt is cheap and you are (assuming) a dual income high earning household. 

It can also be instructive to look at per door prices to give you an idea of where you fall in the market, but the actual value is based on earnings.

The loan was fully assumable when I was ready to sell and I held an owner financed 2nd for part of my equity so I earned interest on it too. 

I’ve become quite obsessed with the world of real estate investing and wish more women decide to jump in and earn their wings on the way down.