4 Simple & Effective Tips For Your Vitamin C E + F 1. Use with sunscreen Apply a vitamin C serum before your a.m. moisturizer and sunscreen. Using both Vitamin C E + F and sunscreen daily has been proven to reduce signs of premature aging. 2. Tightly close the dropper Make sure to tightly close the dropper after every use. This prevents this product from oxidizing faster than it should. Learn more about oxidation here. 3. Using our Needle-less Serum? Apply Vitamin C E + F in the morning after cleansing and Needle-less Serum at night after cleansing. 4. Make it a routine Combine your Vitamin C E + F with these products for the best results Needle-less Serum Broad Spectrum SPF 45 Hydra-Fader