Moisturizer is the key to a flawless face. In fact, the first step in your makeup routine should always be a freshly washed, moisturized face. Why? You want a smooth, clean surface so your foundation will work correctly. Dry or oily patches could create an uneven, discolored look.
Even if you're not a makeup expert, you probably use a daily moisturizer -- and if you don't, go out and get one already, for heaven's sake! What you buy will depend on your skin type. For example, people with oily skin should steer toward light, oil-free products, and if you have dry skin, you'll want a more intense moisturizer.
And if you don't have an under-eye moisturizer, now's the time to add one to your arsenal. In the same way a facial moisturizer readies you for foundation, a good eye cream will make concealer look better.