Never clean your sunglasses with paper towels or clothing, which can leave scratches. Just use clean water and included cloth to clean it.
Never leave your sunglasses under car's front window, especially in summer. Prolonged exposure to the oven-like temperatures inside a car can degrade the lens.
Please don't put your sunglasses in your purse without a protective case. Because the inside of a bag often filled with key or other loose objects, which will cause the sun glasses damage.