Your skin is made of three different layers: the epidermis, or the outermost layer of your skin; the dermis, the middle layer that contains blood vessels, nerve endings, and oil and sweat glands; and the hypodermis, which is mostly made of fat and contains your hair follicles. Moisturizers help that top layer retain moisture -- and this keeps skin smooth, too.
The best time to apply a moisturizer is right after you step out of the shower or bath. With your skin still damp, apply the moisturizer so your skin will keep that moisture in. You can also apply after you wash your hands and before going outdoors for extended periods in cold weather [source: Mayo Clinic].
Make sure to pick the right kind of moisturizer for your skin type. Water-based moisturizers are fine for skin that's neither too dry nor too oily. If you have dry skin, a heavier, oil-based moisturizer may be necessary, because it won't evaporate. Oily skin still needs moisturizing, but be sure to pick a water-based moisturizer that won't block up your skin's pores; look for the word "noncomedogenic" on the label.
If you're taking care of your skin but ignoring the rest of your body's health, then you're losing half the battle for smooth skin. Next, we'll see how what you put in your body can help or hurt your quest for smooth skin.