How can you use Twitter most effectively? Marketing strategist Dorie Clark explains how you can leverage it to listen to your customers, build relationships, and grow your brand. This is an excerpt of a recent talk Clark gave to the New England Society of Association Executives. Clark is the author of the forthcoming What’s Next?: The Art of Reinventing Your Personal Brand (Harvard Business Review Press, 2012). Learn more at www.dorieclark.com.