1).First of all,REDUCE, REUSE AND RECYCLE.
2).Also, less driving means less emmisions.
3).Replace your light bulbs.
4).Buy energy efficient products.
5).Use less hot water(that change alone can save at least 500 pounds of CO2 annually in most of the households.
6).Plant more trees.
7).Encourage others to conserve.
8).Use the 'off' switch.
9).Use less heat and air conditioning.