Concealer

"The best thing is to look natural, but it takes makeup to look natural."

- Calvin Klein

Apply several dots of concealer under the eyes close to the lashes. Apply a dot to the inside corners of the eyes. You can use your finger or, for best results, use a concealer brush or beauty sponge.
Using the pad of your middle finger or your brush, tap in the concealer (always tap, never rub). Make sure to blend well. You can also use your index finger. There's no real rule to it, but I find the middle finger tends to be more gentle.
Apply concealer on other uneven spots on the face — including the chin, and around the nose and mouth if need be — and tap in.
Apply another layer if you need more coverage.
Dust fine, loose powder over your face to set your concealer.