I think there are four elements to getting, and keeping, healthy and radiant skin.
1. Eat the right diet - plenty of fresh fruit and vegetables, nuts and oils, and low in saturated fats and sugar. This will ensure your body has the building blocks for good skin.
2. Stay hydrated. If you haven't drunk enough water, then your skin will look dull and lifeless. Keep topping up that bottle all day, especially if you work or live in an air-condition environment, which is very dehydrating for the skin.
3. Cleanse your skin morning and evening with a gentle product. Never go to bed with makeup on. The chemical residues are bad for your skin and more likely to lead to breakouts.
4. Use a sunscreen every day. Although you need sun for Vitamin D, wearing a sunscreen with broad UV filters (A and B) will keep your skin looking younger longer. Most ageing damage comes from UVA rays, and protection against these is unrelated to the SPF of the cream. Pick one especially formulated for the face, and check the number of stars it has to protect from UVA rays.
Follow these four tips, and you will have healthy and radiant skin that lasts for many years.