It's never too early to pick up good skin care habits. Moisturizing and applying sunscreen daily can help hydrate your skin and protect it from dullness. If possible, avoid the sun when it is at its brightest, from 10am to 4pm.
Hot water, foaming cleansers, skincare products containing alcohol and harsh soaps can weaken the surface of your skin by stripping away oils that retain moisture. If you've noticed your dull skin is due to dryness, try taking lukewarm showers, and lather up with fragrance-free and soap-free suds, like Cetaphil.