Here’s an easy tip from my sister: don’t leave the refrigerator door open! Instead of opening it every single time you need to get something out or put something away, save energy by waiting until you have a few things you need. Every time you open the fridge door, you raise the temperature and the fridge has to work harder to cool everything down, wasting energy. I usually try to think about what I need before I open the fridge, grab it all and then wait until I’m done with every individual thing before putting them away. This obviously doesn’t work for cooking processes that take a really long time, as you don’t want to leave your milk sitting out for an hour or whatever, but it’s pretty easy to take just a second to think about what you need. Same goes for unloading groceries. I usually group all the refrigerated items together on the counter and put them all away at once, instead of opening the fridge every time I take something perishable out of the bag.
Also – no standing in front of the fridge looking for something to eat! It has the same thing every time you look!