Activism 

Create/use/modify/distribute Free Software 
Promote privacy
Promote anonymity
Promote Open Standards and Free of access Standards
Join / Help / make a donation to an association (FSF, EFF, FSF Europe,...)
Boycott and talk about products including DRM
Use correct terms (from GNU/Linux to not use "Intellectual Property"...) 
Promote Free use of Cryptography 
Local activities are important (from LUG to universities/schools)