Sun is good for your skin, just dont overdo it. If it turns red or peels, then you have UV damage and leads to skin cancer. Dont use a suntan lotion with a SPF of more than 8 or else you wont get the benefits of the sun. Dont sunbathe or use tanning beds.
Vitamin C is the building block of collegen, which is what builds the skin. However just eat your fruits and vegetables (oranges, potatoes) as the liver stores about a 3 months supply of vitamin C and too many vits can lead to toxicity.
Vitamin E topically is good. Get a good skin cream with Vit E that doesnt have water listed as the first ingredient.
Omega-fats are used by the body to protect cells, so in general would be good for the skin.
Lots of 100% water.