Changing light bulbs
When you leave a room, close the lights !
When you leave your house, close the lights other then the presence lights.
When you get to sleep, close the lights in the house and also the exterior lights.
Changing, in the house anywhere where there is a big lightning, the light bulbs for light bulbs of a smaller power (less of watts) is not necessary. For example, replacing the corridor 100 watts light bulbs for 60 Watts light bulbs. They need less power. You can also use graduated switch to minimise your using.
With many little actions like this one add up together, in one year, you will save some money and help the planet !