I commend you on your focus and determination at such a young age and encourage you to continue networking and learning via social media as well as here on Bigger Pockets. 

What do I do, given that I want to continue to buy properties for passive income? 

I've had a few discussions about the best way to create a plan in order to "snow ball" your way to owning many REI properties (buy and hold for rent).After Googling around and even reading blogs on this site, I've thought about doing something like the following:Buy my first rental property (SFH) with cash (around $60-70k) where I'd expect about $500 cashflow per monthCurrently I have about $105-110k available (after taking out an emergency fund)Then shortly after, buy my second rental property (SFH) but take out a mortgage and put down around 25% on a $60-70k houseThe cash flow on this property specifically would likely break even (at or near 0) but this would be on a 15 year mortgage and I can use some (or most) of the cash flow from the first to help pay down that mortgage faster, along with my corporate job monthly savings tooI feel I could pay it off anywhere from 5 - 10 years depending on the exact strategy If/When I get the 2nd one, then shortly after that, try and get a 3rd SFH rental property and continue this snow ball effect to build up by rental portfolioObviously this is easier said than done, along with risks and I honestly do not have any real experience with rental properties as this is my first time diving into this type of investing.My main questions would be -- Has anyone done a similar strategy to help build their portfolio quicker?

It continues to rise in value.

Screening applications is the most important aspect of being a Landlord; screw that up and everything else goes wrong.If you don't know what you're doing, consider hiring a professional the first time or two until you are educated enough to handle it on your own.

Continue on down the line with people you know from other organizations/groups that you meet up with (e.g. church, etc.).

But it's just a series of educated guesses, really.

You just need to educate yourself on the technology available today.

Get educated and jump in.

I pay fees, then i pay 150 /360 * interest. ( i will pay 5 months and after that will continue paying interest till it matures).In your example j get a sense i will pay more Heloc.