This will likely include the usual suspects — Facebook, Twitter, and Foursquare — but don’t discount newer sites like Google+ and Pinterest, or Yelp and other review sites or forums. There are niche sites for quite a few industries as well. For instance, those in the travel industry should look at TripAdvisor and FlyerTalk. Identify a few of these more narrowly focused sites and see if your audience is active there.