One of the best ways to "shop your stash" of makeup is to find different uses or application techniques. I'm going to go through a few here, but I want to hear your best ideas in the comments!
1. Before: Cream highlighter After: Cream Eyeshadow
Cream eyeshadows can be hard to apply sparingly and may turn into a glitterbomb on your face. If you can't work with it, try using it as an eyeshadow base or an eyeshadow itself! As highlighters are often pink, gold, and white, these could be great neutrals.
2. Before: Crazy Matte Pink Eyeshadow After: Bright Pink Blush
You might have thought the pink eyeshadow was amazing when you bought it, but you're upset with how few times you've used it. Using it as a blush gives it new life!
3. Before: Drippy/Flaky Mascara After: New Wand!
Once you've bought a less than wonderful mascara, it's tempting to just rotate it to the back of your collection as a backup in between your better mascaras. Instead, wash out your wand with some soap and water until the water runs clean; then use your cheapest possible, non-flaking mascara. Bonus points if you're using a mascara with a great formula but a brush that doesn't work for you
I hope these tips help! I've been using the mascara technique for the past two months and the cream highlighter for the past few weeks!