I'm in my 20s, and the key to skincare in your 20s is "too much is as bad as too little." Rather than slathering on tons of supposedly good functional products, it's crucial to master the fundamentals of cleansing and UV protection. In the morning, I wash my face with water or a light, slightly acidic gel cleanser to remove any accumulated dirt overnight, then layer on a moisturizing ampoule to combat any dryness. The most important thing is sunscreen. Applying a generous amount, the size of a 500 won coin, can prevent aging 10 years from now. In the evening, removing makeup is crucial, so after a thorough double cleanse, lock in moisture with a ceramide cream to protect the skin barrier. If you have any whiteheads, don't touch them and soothe them with tea tree oil—this is the secret to avoiding scars.