To name a few:Base your underwriting on how you will operate the asset, not based on how it is currently operated or based on the broker's pro formaCreate a budget for each year you plan on owning the property + sales assumptionsHave an upfront operating account fund in addition to ongoing reservesBased the market rents on your own rent comp analysis, not the broker's rent comps15% contingency on top of interior and exterior rehab budgetConservative annual income growth assumption (no higher than 3%)

Additionally, this would give you experience in property management, however, a bank might not like the fact that you want to use a loan product (HELOC) to open up another loan product (mortgage).

Your biggest goal right now should be getting a decent W-2 job (assuming you don't have one yet, but if you do, congratulations again) to justify both your college debt and additional debts to secure real estate.

Additionally, he is probably not motivated to leave since he is living for free right now.

@Mike Dorneman that was my thoughts exactly, would be to find a partner that has a process in place and bring additional funds to the table that would allow them to either move into larger deals as you mentioned or a greater amount of units in a much shorter time frame.  

Purchase price: $300,000 Cash invested: $15,000 Bought this house purposely close to a college and lived in one bedroom and house hacked the additional 4 rooms, Dropping my house expenses down to approx 200/month.

Sounds like I'm paying an additional .375% and it's out of my control. 

I will strongly consider it as an addition or change to my lease.

All the income through the duplex is untouched other than going toward expenses as it is solely being used as a retirement investment as will additional real estate purchases.

The context being today's market.Assumption: the new asset would be in addition to your existing positive cash flowing portfolio.Requirement: the new asset’s cashflow cannot be negative.