Write the "date opened" on things in your fridge

Helps me avoids tossing something perfectly consumable when I'm cleaning the fridge.

I only do this for items I use a little of at a time, like a jar of pesto or tomato sauce. I wouldn't waste my time writing it on something like oat milk, because we use that up so quickly.

It's also helpful to write on leftovers. You can put a little piece of tape on the container and write the date.