You can find me on LinkedIn or Facebook if you are curious.I own four SFH rentals which I bought as majorly distressed properties and rehabbed.

Be apart of RE groups/run one, become a thought leader (blogs, youtube channel, podcast of your own or go on others, linked in, facebook, etc), Join non-profits and become a leader, get in with a group of successful professionals (Doctors, Lawyers, Dentists, Athletes, etc) and add value to their profession, team up with other syndication companies and talk about what you are doing with everyone that you know. 

-Start posing blogs, linked in articles, BP posts, Facebook posts, etc.

Then you can also search the owner's name via FB or Linkedin and you might get a hit that way.Then there are paid services as well.

I use the linked in pro finder service.

Places that have really hit home for me and spending very little money would be FB groups, Craigslist (minimum of 30 post), ConnectedInvestors, Linkedin, Meetup, Reverse Searching MLS, Trulia, Zillow. 

Initiate relationships with other note investors and asset managers (LinkedIn is a great tool for this).

Research their name on google and on all social networks and LinkedIn to do some due diligence4.

Facebook, LinkedIn, Twitter, Instagram, etc. to see if they are there. 

Basically the only person I read on linkedin.