First things first: Your Skin

The most common mistake I see women make is with their basic skin care -- they don't have any. All women have skin, but few care for it.

There are 3 basic steps every woman (and person, really) should take for their skin: Cleanse, Tone, Moisturize. Regardless of skin type, those are the steps that should be followed.

Cleansing, which is pretty self explanatory, removes makeup and soil from the face.
Toning will remove any residue from the cleanser, and will pickup what the cleanser left behind.
Moisturizing will keep your skin looking it's best.

Now to do this, one must know what their skin type is: Oily, Dry or somewhere in between? Sensitive? Acne prone? They're all different, and most people experience a combination everything at some point in their life. Telling the difference isn't as hard as it seems:

Oily skin tends to show shine early in the day, usually before noon. Oil is noticed across the entire forehead, on the cheeks, the nose and chin.

Dry skin tends to not have shine at all.

Normal/Oily and Normal/Dry skin are very similar. The oil is in almost the exact same spots -- T-zone and a little on the cheeks and chin. The difference is in how the skin feels without moisturizer: dry skin feels tight.

Acne Prone skin is skin that breaks out regularly, typically associated with teens and young adults. Acne can be present in the form of blackheads, whiteheads and cystic acne.

Sensitive Skin is skin that is, well, sensitive. To anything. To everything. Skin that turns red, or that has a condition, such as rosacea, eczema, psoriasis, etc. 

Acne prone and sensitive skin should be under the treatment of a dermatologist, but there are some over the counter items that can help the symptoms.

Once you determine you skin type, you can determine how to care for it - and then how to make it up!