Turn off the lights when you leave the room.
This is a pet peeve of mine.
Since I start working so early each morning down in the basement of our home, my daughter is left upstairs to get ready for school. After she gets picked up for school, I go up to lock the front door after she leaves. More often than not, I go upstairs to find the TV is still on, the lamp by the couch is on, as well as all the overhead lights and lights going up the stairs. Of course, I remind her daily to turn all these things off before she leaves each day.
She is not the only guilty one. I have a bad habit of leaving the light on that goes down to the basement. Since I spend so much time down there, I find I leave it on so I don’t have to keep turning it on. But, I spend hardly any time in the actual hallway/stairway. So, my new habit will be to turn it off once I am down the stairs.
Now that it is recommended to use LED light bulbs, any extra use that can be gotten from each bulb is good. They are not cheap to replace!