You can try DU's Activist HQ to see what's cooking in there.

You can learn all you can in the Election Reform forum, then educate others in your community.

You can meet other DUers in your region by going to the State and Country forums.

You can access all these DU resources without a being a DU donor.

Mostly, though, I'd Google "election reform" and your state or city to find out what grassroots actions are already underway in your community, then go to their next meeting. Reform movements really are built one person at a time, by people who show up to do the work.