Vitamin C serums are believed to reverse the signs of aging, reduce hyperpigmentation, and fight sun damage. If you’d like to make your own, you need vitamin C powder and filtered water. Add aloe vera gel to heal damaged skin. Use jojoba oil if you’d have extremely dry skin. Stick with glycerin for a basic serum. Ensure that the pH of your serum is at 3.5 and store it in the refrigerator.