Forget fluorescent bulbs, forget lowering your heat settings. These two things are listed as the "easiest ways to lower your carbon footprint", but really these are a drop in the bucket compared to making lifestyle changes.
Change your lifestyle to make a real difference:
1) Move your household to within walking distance of your work. Make sure there is a decent school, grocery store, and transit access also within walking distance. Save the car for long trips or get rid of it entirely.
2) Get rid of lawns, lawnmowers and ornamental landscaping and replace with food crops. An area of garden space 8 feet square can produce all the vegetables needed for a family of 4. Food gardens are tended by hand rather than mowed, saving tons of CO2 emissions per year. If your home doesn't have a lawn, you can still make use of balconies, parking spaces, and roof tops by using the raised bed method of food production. If you are replacing a large lawn then replant with fruit trees, asparagus and other space hogging produce.
3) Support local farmers and learn to do without foods that must travel great distances to reach the market. Pineapples, mangoes, bananas, and oranges are examples of carbon expensive foods. Choose locally grown produce instead, such as apples, kiwi and cherries.
4) Buy fewer electronic toys and shut electronics off by unplugging them or using a power strip rather than leaving them in "Stand-by mode".
5) Reuse materials first and then recycle what is left. Refuse to buy items that are over packaged. Use cloth shopping bags. Take plastic bags back to the store where you got them, many stores will be happy to re-use them. Re-use plastic food boxes rather than buying tupperware. Refill juice bottles with homemade iced tea.
6) Stop buying bottled water. Get a good filter system and re-use the bottles you have.
7) Put up a clothes line and use it as often as possible. Use gray-water to water your garden. Use less detergents and soaps.
8) Donate usable items to charity and shop in charity stores first for items you need.
9) Take care of items so that they will last longer.
10) AFTER you have mastered the first 9 items on this list, then you can worry about fluorescent lighting and turning your heat down 1 degree.