In my experience professional societies are great to meet your competitors and to get an occasional job. I'd start by targeting a certain market (probably not national TV or Film)like corporate B2B, POS marketing companies or something a bit off the radar.
Also, if your the creative type find someone that is your counterpart in sales and marketing to help sell you, generate leads, and to overall get your name out there.
Get a demo online if you don't have one and start combing the production websites, craigslist, ad agency boards, and the like for freelance ops (be careful there area lot of vultures out there).
The reel is the most important thing and personality a close second.
Once you get the first big hit others are sure to follow.