“Always give them something to do,” advised Karen Taggart, manager of fund-raising innovations at People for the Ethical Treatment of Animals. That was the philosophy behind PETA’s online campaign against Chinese fur farms, which paired donation appeals with a variety of interactive options for supporters such as links to petitions and videos and an opportunity to forward information to friends. “Every time someone clicks on a link, you’ve just increased the likelihood that they’ll do something else for you in the future,” she said. That campaign attracted 1,028 new donors to the organization, said Ms. Taggart.