Ask HN: Online Security Tips for Newbie Freedom Activists?

I'm becoming active in a local group of citizens (constituents of one electoral district here in the United States) who are trying to promote protection of civil liberties. Many are quite new to any kind of political activism and quite a few are very new to participation in online networks. What are your recommendations for sources of advice on best online security practices, easy for beginners to understand? The local group includes some technology professionals familiar with online security and administration of websites and mailing lists. The group plans to build a public-facing website, an internal use website, a mailing list for group participants, and other online channels of communication. It already operates a Twitter account and Facebook group (which is becoming quite active) and hosts in-person meetings. I would appreciate tips to pass on to new members about personal Internet security best practices and resources for nonprofit organizations or political action organizations to maintain secure communications in a possibly hostile environment.

Thanks for any suggestions you have.