An unchanging routine all year-round

People tend to self-type their skin and think of themselves as having that skin type year- round. While your skin itself doesn't change, what your skin  needs does change with the seasons (as well as life-changes like pregnancy and age). You need a heavier moisturizer in winter than in summer, for example, or a lighter one if you travel from a cold climate to a warm, humid one. it's important to periodically reassess what your skin needs at that moment in time.

Not using sun protection on a daily basis

With all the moisturizers and makeup products out there with SPF built in, there is no excuse for this beauty blunder!

Overaggressive cleansing

Cleansing too often or using products that are chemically too aggressive for their skin type is huge mistake. How can you tell if you're making it? Your skin will feel drier than it should be and may even break out a bit. A cleanser should clean without destroying the skin's lipid barrier.