Use a product that is two shades darker. This will put the area in the shadows.

(Thanks to Scott Barnes Cosmetic Book for the photos)
You want to use a Powder or Creme Finish with no type of sheen/sparkle:
A Contouring Product Can Be: | |||
Blush | Foundation | Face Powder | Eyeshadow |
Lipstick | Base | Paint | Concealer |

(Created the montage using google.com images.)
Matte | Eyeshadow, Blush, Face Powder, Concealer |
Cream | Base, Concealer, Paint, Foundation |
Liquid | Concealer & Foundation |

(Created the montage using google.com images.)
Depending on your face structure contouring can benefit you:
- Add dimensions to your cheekbones
- Bring your lip area out more
- Shorten the tip of your nose
- Slim the width of your nose
- Slim your face
- Hide a double chin
- Add depth to your eyes
What brushes to use?
*Using MAC Brushes just for an example:

(Created the montage using nordstroms.com images.)
#109: blend or contour powder products
#188: Ideal for creating soft layers or adding textures
#191: Distribution and blending of liquid, emulsion or cream products.
#195: precision application and blending of all concealer formulas.
#190: A foundation brush designed to create even finish, flawless look.
#224: Tapered blending brush.
#275: A medium angled Shading brush.
#227: Use for applying, blending or highlighting any powder-based products.
#168: Large contour angled brush
**You can search the Blog or my channel youtube.com/dominichulinda to see what I use.