What can you do to conserve/reduce energy costs?

I was taught by my teacher in highschool how to save energy. And they are small but very effective ways to save energy. She told me, I can set the iron to zero, 3 minutes before ending the ironing because the wasted heat can still be used instead of letting in cool down. She told me to unplug the television when not in use because it still consumes energy even though it is not turned on. And this also applies to other appliances. When using an electric fan, be sure not to let it rotate to other sides when you're the only one in the room. Turn the lights off when no one is in the room. My teacher was also environment-friendly person that she even told me that after brushing my teeth, I can swallow the paste so that I will not pollute the environment. I thought it like killing myself with that practice, swallowing toxic substances. She was a weird teacher for me.