There are a number of sites that will help you remove your name from direct mail (i.e. junk mail) mailing lists. Register with them and save energy and resources being wasted on delivering to your mail box a bunch of crap you have no interest in.
Open your curtains in the morning to let solar energy (aka sunlight) in to warm your house, and close them at night to help keep it in. Sometimes it's tempting to close curtains during the day to darken a room, but remember that you're wasting free solar energy.
If you want to green your home by adding/changing insulation look for companies that sell reclaimed insulation. You get to save energy twice! Check the link below; they sell all over the country.
Save your plastic easter eggs for next year. One bag of plastic easter eggs will last you many years if you gather them up and save them. Just add new prizes (we usually use small pieces of chocolate and money.) If your kids have outgrown them, pass them along on freecycle. There's no need to repurchase them every year.
Use power strips for things like TVs, A/V components, video game systems, etc. When not in use, turn off the power strip to cut power to everything. Even when turned off, things like TVs consume power, so using power strips to control several components at once makes turning them all off much easier.
Recycling isn't just for bottles and cans anymore. Check with your local recycling company to see what you can include. In many places you can recycle broken down boxes, junk mail, magazines, and more. Think carefully about your trash, and recycle everything you can.
If you want to buy organic foods, but can't afford the extra cost, choose the foods that are typically higher in pesticides to buy organic. These include: apples, bell peppers, celery, cherries, grapes, peaches, pears, potatoes, raspberries, spinach, and strawberries.
If you plan to drink your coffee at Starbucks, tell the barista that it's "for here." They'll put it in a mug for you rather than a paper cup.
When you are washing your hands, don't leave the water running. Since you should be scrubbing your hands long enough to be able to sing the ABC song, that's a long time to leave the water running, especially if you aren't actively using it. Turn it off after you wet your hands, and back on when you're ready to rinse. You'll save a lot of water.
Check with your local grocery store to see if they recycle plastic bags. Most do these days, and even if you use re-usable shopping bags for your grocery shopping, you can bring in other types of plastic bags like ziplock bags or other bags used for food packaging to be recycled instead of just adding more plastic to the landfills.