http://www.foreignpolicy.com/articles/2013/10/24/the_dissidents_toolkitFrom the article:
Attracting participation is perhaps the most important of these tasks, since the ability to provoke defections and outmaneuver opponents often depends on whether the movement enjoys large and broad-based support. The most important singular factor for a successful campaign is its participation rate. According to the NAVCO data set, which identifies the outcomes of over 300 nonviolent and violent campaigns worldwide from 1900-2006, none of the cases failed after achieving the active and sustained participation of just 3.5 percent of the population -- and some of them succeeded with far less than that. Of course, 3.5 percent is nothing to sneeze at. In the United States today, this constitutes over 11 million people. But how do movements get this large in the first place, especially in countries where overt participation in a mass movement is highly risky?
One way organizers can grow their movement is by including tactics that are safer and therefore more attractive to risk-averse participants. For example, instead of relying solely on demonstrations or protests, many movements will allow people to participate through "electricity strikes" where people shut off their electricity at a coordinated time of day, or by banging on pots and pans in the middle of the night to signal the power in numbers. Engaging in these types of actions may draw in more ambivalent people while also allowing them the opportunity to develop a sense of identity with the movement and its goals. In Chile under Pinochet, for example, outright demonstrations against the dictator were far too dangerous. In one instance, Pinochet was so threatened by the subtext of some popular songs that he banned public singing; it didn't take much. But when people began to bang on pots and pans, it let them demonstrate their defiance anonymously in the safety of their own homes. As the people's metallic clamor for change became louder and louder, anti-Pinochet organizers and their supporters became emboldened to press for more disruptive and overt action.