Unplug. Leaving devices plugged in, such as laptop chargers or toasters, can eat up "phantom" energy. Even when an appliance is turned off, it may still use power. Try unplugging when possible.
If it will be at least 36 hours before you use it again, unplug it.
Turn lots of things off with a power strip. You can plug all your appliances in one area — say, your computer — into a power strip. Then when you're done using all appliances, simply turn the power strip off at the switch.