You can check out this tool on the power of 350.org, but their toolkit dedicated to helping activists understand, host or run powerful and popular workshops (climate change or otherwise!) deserves its own spotlight too.
Here are the segments that 350.org offers. Each one builds on the next, so that you can lay the groundwork and then build the movement!
Telling your story
Build a movement
Build a campaign
Media: Online and Offline
Putting it all together
Extras: Tips, games, planning
Each segment is complete with an agenda and timeframes to keep you on track, a powerpoint presentation, notes for a facilitator, and any guides/materials for participants. While the workshops are primarily focused on environmental organizing, there are tons of great ideas (particularly in opening sections discussing leaderships, teamwork and group dynamics) that could be applied to a lot of different activist efforts.