Like it or not this industry is headed for consolidation with Zillow and CoStar (Apartments) becoming the two dominant players.  

Finding an A-player realtor is going to be the key because the realtor will have contacts to contractors, property managers, title company, real estate attorney, and insurance agent.

It's good to know the marketplace and who the players are in the area where you are looking to generate business.

Something that will catapult you in is establishing a working relationship with a real estate player who you respect.

People who buy and sell regularly will know the market and the players.  

After a quick look around on both Facebook and the internet, in general, it seems like no-danish based property invest forums exist (perhaps I should start one?).

Look at places like Oahu where overnight 90% were made illegal.2, SFHs are dollar for dollar very inefficient, financing is easy and they are more liquid but your most valuable asset is time so if you go into STRs and SFHs you could find yourself at a loss of years before you gain traction.3, Watch what the big players are doing (I know that some hedge funds are buying SFHs but not at the rate as large multi-family)4.

I'm just saying that even as a small player when compared to the big 5, nothing I do is without scrutiny as a lender/investor from some ambulance chaser looking to shake a few bucks off of my tree.

Pro poker player eh? 

I also believe that much above $4M and you are starting to alienate the majority of the private market buying this product type (my target market), and with the limited number of substantial players in this industry the majority of these transactions will be done principle to principle.