Improper use of vitamin C can either worsen or improve your skin’s overall condition. And here’s why. When you see people with glowing skin, they usually use vitamin C. And here’s how to use it correctly. Cleanse your skin with a foam. If you have sensitive skin, always apply a gentle, hydrating, moisturizing toner before the serum for best results. Apply vitamin C on completely dry skin. So, let your skin dry. And next, we apply the 7-day serum with vitamin C and ascorbic acid to lighten pigmentation and post acne and give your skin a healthy glow.