Low cost solutions.
May cost you some moola but worth it.
 
Electricity:

Use Compact Fluorescent Bulbs: Replace 3 frequently used light bulbs with compact fluorescent bulbs. According to the energystar.gov, if every U.S. household simply replaced one traditional light bulb with an energy efficient compact florescent lamp (cfl) we would save enough energy to light 3 million homes and save $600 million in utility bills AND prevent greenhouses gases equal to the emissions of more than $800,000 cars. Wow...so if you are going to spend money on one thing this would be it. 

PLEDGE to replace at least one light in your home with one that has earned the ENERGY STAR.

Cost: All over the map. As high as $10.00 a bulb to as low as $10.00 for 10. So look for special offers 

Appliances:

Check your refrigerator and freezer gaskets: The gaskets seal the door keeping the cold air in. Check by using the 'paper test'. If you can slide a piece a paper, or a dollar bill between the closed doors then it's time to replace your seal.

Cost: Average prices $50-$70, depending on make and model of your refrigerator.

Heating and Air:

Change the AC Filter: The most important thing you can do to keep your Air conditioning energy efficient is to clean or replace dirty air conditioner filters. Save 350 lbs. of carbon dioxide and $150 per year. Prices vary depending on size.

Water:

Install a Low-Flow Showerhead: Using less water in the shower means less energy to heat the water.Save 350 lbs. of carbon dioxide and $150.
Eartheasy sells one for $16.95

Vehicles

Change Your Air Filter: Check your car's air filter monthly. Save 800 lbs. of carbon dioxide and $130 per year. Prices determined by vehicle, year and make.

Paper:

Stop Junkmail- an overwhelming task on your own but the company 41 pounds will contact dozens of marketers to stop your junk mail, reducing the waste.  $41 for 5 years and they even donate 1/3 of the fee to the environmental or community organization of your choice.

Buy Minimally Packaged Goods: Less packaging could reduce your garbage by about 10%. Save 1,200 pounds of carbon dioxide and $1,000 per year.                                                                    

Plant a Tree: Trees suck up carbon dioxide and make clean air for us to breathe. Save 2,000 lbs. of  carbon dioxide per year.
                                               
Use Recycled Paper: Make sure your printer paper is 100% post consumer recycled paper. Save 5 lbs. of carbon dioxide per ream of paper.

Bring cloth bags to the Market:. According to the Food Marketing Institute (FMI), the average American makes 2.3 trips to the grocery store each week. Walk away with five to 10 bags each time (not hard to do if you're feeding a family of four) and that's between 600 and 1,200 bags per shopper each year. Or 40 billion grocery bags each year.

Buy Organic Food: The chemicals used in modern agriculture pollute the water supply,and require energy to produce. Also buy local, food doesn't have to travel far which reduces carbon dioxide emissions and packing materials.

Unless otherwise noted, calculations are from www.stopglobalwarming.org