You can mitigate almost all of the risk by just hiring an excellent property manager. 

With the financing ready, your team in place, the market research complete- hire an investor friendly realtor.

Best practice is to do this type of modeling after you've seen the property and gotten the reps to know what all the numbers mean.

@Paul BogardTo rent out multiple bedrooms in Philadelphia, understand zoning regulations, consult a knowledgeable real estate agent, hire a property manager, and consider multi-unit properties, student housing, and co-living spaces.

Note that if you are married filing joint, only the spouse who is qualifying for REPS is able to count their hours.Step 4: Apply the quantitative testsPer Section 469(c)(7)(B), in order to qualify for REPS, you must meet both of the tests below:750-Hour Test: If you materially participate in a real property trade or business, you must spend 750+ hours during the tax year.More Than Half Test: You must spend more than half of your personal service hours in the real property trade or business in which you materially participate.Step 5: Material participation in rental activities Just because you qualify for real estate professional status does not mean that your rental activities are automatically considered non-passive.

Once you have REPS the distinction between passive income (or losses) and active income (W2) disappears and all those tax losses you have been banking can be applied to the W2.Good luck

If you are claiming Real Estate Professioanl Status(REPS), it is important to keep a log of your activities. 

(Inspectors are generalists, so specialists are essential for plumbing and electrical issues in older homes.)Structural Concerns: If potential structural damage is spotted, hire an engineer to assess it properly.Be Diligent and Proactive: Old homes often require extra due diligence.

An agent can help with flips and be aware of the new NAR rules that you'll have to sign a rep agreement before viewing a property

This is a great case study on reasons to hire a property manager - it's the headache part...