1) Read one authoritative book on global warming. Al Gore's book version of An Inconvenient Truth is excellent, but just in case you don't trust his take on things, here are some other titles to consider:
- Field Notes from a Catastrophe by New Yorker staffer Elizabeth Kolbert
- The Weather Makers by Australian scientist and Man of the Year, Tim Flannery
- The Discovery of Global Warming by Spencer Weart
- What We Know About Climate Change by MIT climate scientist Kerry Emmanuel, (the shortest and most accessible of the bunch.)
3) Conduct a home energy audit. Find out how much power you use domestically and where you can trim it down. Pick the lowest hanging fruit first -- things like extra insulation and more efficient lighting can make a world of difference.
4) Experiment with alternates to driving. Maybe you can telecommute to work once or twice a week. Or carpool? How about riding your bike to the store for that half gallon of milk?
5) Measure your carbon footprint and consider what it would take to become carbon-neutral.