Your lips require moisture to look full and plump. The first thing you should focus on is hydrating your body. Dehydration will most easily be noticed from your lips.
Our lips will shed their top coat every 28 days. However our lips DO NOT have melanin so they are more easily susceptible to sun damage.
Try to cover up your lips using a scarf when in extreme weather conditions.
Lips unfortunately do not have sebaceous glands so they cannot regulate their own moisture.
Avoid liking your lips often as this will dry out your lips because of the digestive enzymes in your saliva that break down food. Look for lip balms that contain a hydrating feature. Oil based lubrication is always best. Opt for balms that have an SPF of 15 or higher.