These properties are often more problematic and management intensive.

There is an old rule in finance, never finance a long term asset with short term financing.Lines of credit, or HELOCs are short term financing products, interest can adjust quickly, they can all be terminated at-will by the lender, they can be called due, many have terms that relate to your outstanding credit balances, as you take on more credit they see a higher risk and can increase your rate, cut you off or call it payable.Another issue with small investors, a HELOC or LOC that you draw funds on within 6 months can put you in a position of being underwritten as a cash out refinance instead of a straight refinance on a no cash out basis.

Look on the MLS and find comps for sale (look for sold but you probably don't have access) see what is being offered, adjust the price down to the "average % sold of sale price" that should be in the stats for that MLS, like 92%, or whatever, then look at the asking price at 92%, do about 6 or 8 comps, and you should be very close to market

sometimes that will be adjusted depending on the market, maybe selling a long time rental, or renting a property that is slow to sell.

And that if there are inconsistencies between what the original spreadsheets show and the new documents (there probably will be) then you will have to adjust your offer.

You are not free to adjust it to market rent after occupying it.

The best way is to know the numbers in your market and how the adjustments affect the price (number of rooms, year built, size of the house...etc)That way when you come across a property you will know what is underpriced and you can jump on it.

Generally speaking, you will experience more intensive management, greater demands on your time, and especially, higher operating expenses & turnover with a multi-unit property vs. houses.  

It is absolutely essential that you adjust your game plan on how to proceed in the new terrain of investing.

I then set up daily email alerts for new listings, price adjustments etc...I would then review the daily email and look up those that I am curious about using a bunch of other web sites, Trulia, Zillow, Realtor etc etc etc...I originally selected FloridaMoves.com because it was fairly quickly updated unlike zillow and others seems to be 3 days behind.