Golden skin at the end of the rainbow…
Diet massively affects how you look. Roughly speaking, the foods that make you gain weigh (sugar, trans fast, processed foods, white flour) will also give you wrinkles and spots, while all the stuff your mum told you was good for you (fruit & veg, oily fish, chicken, eggs, nuts, wholegrains…) helps build collagen, hydrates skin and infuses it with cell-protecting anti-oxidants.
The greater the variety of anti-oxidants you eat the better. A very simple way to do that is to eat fruit and veg in as many different colours as possible.