If you wear makeup, check that everything is in good condition and isn’t breaking down. If you aren’t certain how long you’ve had some of the products, search online for how long it’s safe to use things like mascara before they need to be discarded.
If you like updating your cosmetics with the season, then toss previous seasons’ products if you know you won’t use them. If you're bothered by the waste, remember, holding onto something that you don't use doesn't give you more for your money. Consider other options.
On the other hand, if you rarely wear makeup but hold onto a lipstick and mascara for special occasions, ponder if you really need to hold onto old cosmetics for the sake of a few days of the year you use them.
Also, while you’re here, wash your makeup brushes, wipe out your makeup bag or case, and even swipe a tissue over the surface of products to wipe away oils and some bacteria.