@Artur A. really just depends on your long term goals and your investing style.

I think your examples in the other replies, lower in this thread, speak to motive/intention....yours is pure and true to the pursuit of knowledge, and the one i'm complaining about is not...and their conduct/style/motive/intention creates a less than optimal environment for me to maximize the value from my time spent on BP....IMHO  

To me Craftsman Style porch columns make a great statement. 

Makes it difficult to get accurate value because of small sample size.Some infoLocation, affluent west shore suburb of Harrisburg, low crime,  family oriented neighborhoodRanch style, 2400 Square Feet total, everything updated by hvac system (works fine)Each unit has 2 bed 1.5 bath, one is 1400 sq other is 1000Rent is 1450 one side, 1500 the other, renters pay all utilitiesInsurance, maintenance, and yard upkeep total 3000 a yearGood renter clientele, most are doctors or nurses, close local hospitalsBoth have separate driveway and yard  Located in well of neighboorhood in low tax hampden township, taxes are 3500 a yearThe duplex was grandfathered, out of the 400+ houses in the  development, there are only 5 multifamilies. 4 houses down the street sold for between 380-400k in the last 4 months.

As mentioned above, you can certainly use a commercial style loan (and there are some 30 year fixed rate commercial lenders out there) but working with a lender with no overlays on the Fannie/Freddie side is paramountSometimes when I type all of this out it might still not be 100% clear so feel free to ask any questions and I'll be here to help.  

@Nina TelthorstThat's very true.Properties have to be comp'd against "like" properties that are similar in style, size and utility AND that have closed in the last 6 months or so to have an accurate picture of value. 

So if a lender is offering you a portfolio/commercial style loan that will go up to 80%, make sure you are asking the right questions - what is the prepayment penalty, how long is the loan for, how often does the interest rate adjust.  

In more detail, this would be my advice, based on what friends have done:  Buy a house with a lot of bedrooms and bathrooms for its price with a walk-out basement; have other people (usually servicemembers) as roommates, renting by the room; house-hack the basement into another unit, and as long as you don't install a stove you stay legal where you aren't allowed to subdivide but you can still have a large toaster oven, a hot plate, and a full sized fridge; then you have two complete units (local-style) when you are deployed elsewhere that will result in a decent positive cashflow and, if you bought in the right place, probably appreciation; cash out whenever the market surges and invest in somewhere that cashflows better with all your profits.  

I have a duplex (built around 1940) that has an older fuse style breaker box. 

Contributors: Veronica Joubert Purchased a single family rambler style home in Annandale, VA.