In addition to clubs, my preferred method is to approach those whom I percieve to be bigger players than I in the real estate game.
In my market, simply by doing a tax search in our MLS system, with a little finess one can find out who owns several properties.
It may seem a little bold (trust me I have sizable stones), but I have found that that sort of boldness, essentially cold calling the bigger players in the several markets I deal in, find it appealing that I am willing to
1 reach out
2 allow them to help evaluate the prospective deal
3 and ultimately they have consistently put me in touch with thier banker/investors/ point people
And all of those things simply ad to my "stock" and experience as an investor.
As a final thought, looking back at my decade long ride in hands on real estate investing, its always been better (for me) to have an experienced real estate partner than a non-experienced one.