Summarize the following:
Too much sun exposure can cause lip discoloration, including dark spots. Keep your natural lip color safe by protecting your lips with lip balm that has at least SPF 15. It's best to use sunscreen all year long, even in the winter when the sun isn't as strong. Moisturizing your lips helps them look bright and fresh, preventing cracks and flaking. It's especially important when the air is dry and cold. To keep your lips moisturized, do the following:  After exfoliating your lips, always apply a good nourishing lip balm to keep extra moisture from escaping. If you have trouble with flaky lips, try sleeping with a humidifier. If your body is dehydrated, it'll show up in your lips. Start each day with a full glass of water. For each cup of coffee or soda you have throughout the day, drink a full glass of water to make sure you stay hydrated.  When you have alcohol, make sure to follow it with plenty of water. That way you won't wake up with dry lips. Avoid extremely salty foods, since they can dry out your lips. Smoking tobacco products can lead to lip discoloration. It also causes lip wrinkles and thinning. When you're going for a natural red color, it's best to avoid smoking altogether.

Summary:
Protect them from the sun. Keep them moisturized. Stay hydrated. Avoid smoking.