Many on the progressive/liberal/left are feeling discouraged and frustrated by this conservative shift. This shift has happened because of a concerted effort to build conservative think tanks, talk shows, influence the media, and such long term movement building exercises.
Looking at my own life, I don't really know how to actually engage in activism or do things to try and make a positive (for me) change, study groups provide a relatively easy way to pull people in and strength our movement. Looking at how radical women worked, once you have someone at your study group you can start to ask them to do other simple things like stuff envelopes or put up fliers.
For instance, I was thinking about what might be helpful for the LGBT group at Caltech and came up with the idea of reviewing the history of the gay movement, how progress was made, what obstacles were overcome, what techniques worked and which didn't.
Additionally if my half-remembered history is right, second wave feminism started off with consciousness raising groups where women got together and actually talked about the issues they were facing, once educated and informed, and with the support network built by these groups they were then able to move on to social activism.
(Also for the more introverted, the toastmasters program might also be useful. I've tried to do activism before, but haven't been that effective because I keep freezing when having to interact with people.)
Some possibly interesting books Don't think of an elephant or the activist's handbook.