- 241 million monthly active Twitter users and 63% of brands have multiple Twitter accounts. - The document provides tips for using Twitter to successfully market and sell books, including having clear goals, optimizing your profile, posting quality and relevant content regularly, engaging with followers and supporters, and using analytics to improve performance. - The 4 keys to success are having a clear aim or goal, powering up your profile, posting quality substance and content, and engaging with and building relationships with supporters and followers.