Reddit reviews Striking at the Roots: A Practical Guide to Animal Activism

There's activism happening everywhere, and lots of great vegan organizations that need out support (volunteer and financial). A few examples:

• Pay per view activism - Volunteers from the Farm Animal Rights Movement (FARM) pay people $1 to watch a four minute slaughterhouse video, and over 80% of people who watch commit to eating fewer animal products.
  
• Leafleting - This study shows that leafleting is nearly as effective as videos in convincing people to reduce animal product consumption. "Among the treatment group, about 50% of the participants said reading the booklet made them want to eat fewer mammals and birds, and 35-40% wanted to eat less eggs, dairy, and fish."
  
• Making donations - See this intro to effective altruism. And here is a list of the top animal advocacy organizations.
  
• If you're really interested in organizing something on your own, Striking at the Roots is a great guide to effective animal activism.