Vitamin C is an antioxidant and one of the most powerful, it can make it's way past your skin's upper layers and get inside collagen-making cells. When Vitamin C gets into these cells, the production of collagen increases up to eight fold. It will also reduce the formation of melanin, the pigment that causes age spots and protects against free radicals damage.
Be sure to layer a Vitamin C Serum underneath your sunscreen to neutralize the oxidative stress from UV radiation and inhibit melanin production.
When it comes to sunscreens, there is nothing better than a mineral based formula composed of zinc oxide. It offers both UVA and UVB protection, usually at a higher percentage.