When Jennifer Baumgardner and Amy Richards were touring the country to promote their first book, Manifesta: Young Women, Feminism and the Future, audiences repeatedly asked what they could do to “make things better,” This book, Grassroots: A Field Guide for Feminist Activism (Farrar, Straus and Giroux, $14), attempts to answer that question by offering strategies and tactics to aspiring agitators. The book’s premise is simple: everyone can do something to make the world more egalitarian, more humane.