A slow dripping faucet can accumulate over two gallons per hour. Avoid taking baths and long showers. Only turn it on when needed. If you must wash your car at home, only turn on the hose when you're rinsing. During winter months, light a fire for warmth instead of using the central heating unit.
Wood is still cheaper than gas.
Wear seasonal appropriate clothing around the house. Get used to wearing sweaters and pants during winter months. You'll find that you won't need to turn the heat up as high. Lower the temperature on your gas water heater. You really don't need water heated up to 180 degrees.