With age, our skin experiences a decrease in the production of collagen, natural oils, and elastin. This change causes a dryer and less plump skin. The skincare mistakes committed at young age start being visible in the late 30s or early 40s. So, here is an article by Dr. Nivedita Dadu which includes vitamin C serum and 8 other skincare tips for Women above 40.
Ref: Doctor NDTV