One of the ingredients that you will want to try to avoid is high fructose corn syrup. Not only is this detrimental to your skin, but can also add fat and calories to your diet. Typically, high fructose corn syrup is found in sweets, which you should want to eliminate entirely from your diet.
A great nutrition tip is to wash your fruit off thoroughly before you eat it. Fruits such as apples tend to have a lot of bacteria on them, and if you're not washing them off before you eat them, you could potentially get really sick.