The lip skin has two components: epidermis and dermis. However, the lip dermis does not have any hairs or sweat gland.
This means that, without any protection, lip dermis is directly exposed to external environmental conditions. There is no lubrication, chapped lips can easily appear.
Drink plenty of water to hydrate lip skin. Avoid harsh weather, and use lip balm.
Regularly use lip balms. If you wait until you have chapped lips, the recovery will take longer time.
Try not to lick your lips. Do not use fingers to tear off skin flakes, this irritates the skin, and slows down lip care progress.