Typically based of historical figures with adjustments made and explanations as to why you think you'll be able to increase rent & decrease expenses.When speaking with the property manager ask the following to get started:what other properties do they manage:how does this property compare - physically and financially (rents, expense ratio, etc.)What is the going cap rate in the area, what are they basing their asking price off of? 

Older properties may want to lean toward 10%Vacancy rates can be determined several ways: either google vacancy rates for the area and use historical data, or ask several other landlords in the area for their real numbers.For most of my estimates, I assume 10% maintenance, 10% CapEx, 8% vacancy when doing the first evaluation of a property.

We're looking to house hack our way into the downtown/historical OKC area with either a duplex or, more likely, a house and guest house.

Tax => I can deduct home office internet, but for management reporting I would not include that expense - to give an example.5) Sepearate historical perspective from current perspective since rents, late fees etc. change over time.Thanks for any tidbits from your experiences!  

My next step will be to look at historical rates..but hoping that a veteran of the area has the quick answer!  

In my message I listed all the neighborhoods in LA that broke historic records of heat and that it's out of my control.

You might do that for a historical building with constant standing water in the basement.

Historically, tightening cycles lead to recession!

And even though today's rates are still (historically) crazy low, they're higher than 4%.

Now, because rates are currently historically low and rising now is the time to get cheap money.