Conserve Fuel

Mind the basics. Go easier on the gas pedal and shun your A/C if you're just driving around town.
Work with your car, not against it. Clean the junk out of the trunk, let off the accelerator earlier when approaching a stop, speed up before hills to make the climb easier, and use the cruise control more.
Keep those RPMs low. Learn how to skip gears if you've got a stick-shift, avoid engine braking, and reacquaint yourself with Neutral (it's not just for towing).
Take care of your car. Tire pressure, spark plugs, air filters, oil—they all make a huge difference.
Pick the right station. If you can save a whole dollar by going to a different station in town, by all means do it. If the difference is just a few cents, you're probably not saving much by driving several miles to the cheaper station.
Don't drive if it isn't necessary. Public transportation can be a wondrous thing for your wallet, and walking or riding a bike are even better if your destination is nearby.