Use Both Sides of Paper - if you have a printer with a double sided print option use it. You will save half of the amount of paper you would have normally used. Then when your done bring it to the recycle bin.
Get rid of baths - Don't take baths, take showers. You will in average save about half the amount of water that you would if you were taking a bath.
Don't get bottled water - Instead of bottled water get a reusable container to carry water. Also you can get a filter to make your home tap taste more like bottled water. It is definitely more cost efficient.
Turn the water off when you brush - Your parents have said this before, now I say it. You will save 4 gallons of water doing this alone.
Shorten your shower - Every minute you cut from your shower is roughly 5 gallons of water. The less time your shower takes, the lower your impact on the environment.
Recycle Glass - If you do not recycle this, it will take a million years to decompose.
Don't Pre-Heat the Oven - unless needed, just turn the oven on after you put the dish in it. Also, to see if it's finished just look through the glass instead of opening it.
Turn Down your Thermostat - Every degree lower in the winter or higher in the summer you put it is a 10% decrease on your energy bill.
Turn off your lights - An easy one. Turn off your lights when you are not using them. The benefits are obvious.
Get rid of junk mail - There are many services that can help you get rid of junk mail. That will lead to a lot less trees being cut down to take up room in your mailbox.
Use Matches instead of lighters - Lighters are usually considered disposable so they will most likely end up in land fills. You can use the cardboard matches which are much more eco-friendly because they are made of recycled material.