1. Unplug electrical items that you are not going to be using.
Depending upon the item, the amount of money that you save on your light bill can be small to very noticeable depending upon how much you unplug and how much you actually have plugged in to begin with.
2. When a light bulb burns out, change over to the new, yes, more expensive energy efficient light bulbs.
While more expensive, they really do cut down on what you use, they also have a pretty long life and really worth the money and you still get the same amount of light for less money and power usage.
3. Switch over to cloth shopping bags.
The amount of waste and landfill problem that comes from the tons of plastic bags in landfills is a mind boggle in and of itself. If you have ever driven by one, you see them literally floating on the air all around the place. Switching to the cloth bag keeps not only the plastic out of landfills and wasted fuel to make such - it also keeps the clutter out of your home. I don't know about you, but I really THINK that they have babies where I store them and there always seems to be MORE than I put there.
4. Turn up/down the ac/heat 2 degrees.
Doesn't seem like much, but you will notice a difference on the billing.
5. Try to stay away from drinks that come in plastic bottles.
Seems a no brainer, but actually taking the time to plan for a drink that you know that your going to want and bringing your own in a re-useable container.
6. Buy from re-sale shops.
Not only can such save you money, but it saves cutting down of forests, the making of plastics, etc. Even if the chair that you find you have to have recovered to match what you already have - one less tree that is cut down and one less piece of furniture that goes to the city dump.
7. Plan your cooking.
I bake more on the weekend to make the most out of an already heated oven vs. having to reheat several times during a week to fix something that I know that I am going to be eating later on in the week. I also have reuseable containers that I portion control so that when I am busy and don't feel like cooking, I have a ready meal on hand.
8. Do the laundry in cold water.
With the advancement in washing powders, the need to wash in hot water is almost a thing of the past. Also, most of the newer fabrics actually do better when washed in cold water - not to mention that it also cuts down on the color fade problem. Clothes last longer - win/win situation.
I have many more, but these are ones that cost little if anything to make a more positive impact upon the planet. Better a small step than no step at all.