Turn off appliances and lighting. Turn off any appliances you are not using, especially by switching off lights when you leave the room. Don't leave fridge or freezer doors open for longer than necessary, and don't forget that your freezer needs to be defrosted regularly for it to run efficiently.
Turn off your computer. Leaving the screen saver on will not save any energy. Screen savers can use more energy than when you are using the computer yourself and can reduce the life of your monitor. Instead, enable the display blanking feature to automatically turn off the monitor when your computer is idle. You can save $50-$100 per year by enabling your computer to 'sleep' automatically when you are not using.