Unplug the spare refrigerator in the garage. Get an energy audit. Give your refrigerator breathing room against the wall, clean the coils, and don't set the temperature too low. Cut the length of your showers in half. Replace or clean furnace filters once a month.
Dirty filters restrict airflow and increase energy use.
Plug your home's leaks. Install low flow showerheads. Wrap the hot water tank with jacket insulation. This is especially valuable for older water heaters with little internal insulation. Replace incandescent light bulbs with compact fluorescent bulbs.