One of the fundamentals of applying makeup is putting that contour shade in the crease. Everyone just assumes we know how to do it! These tips make it fool-proof.
To find your crease, close your eye and press on it gently. The crease is the indent that hugs the top half of your eyeball.Apply your contour shade in the crease with your eye open. If you close your eye to apply your contour shadow, it will disappear into the crease when you open your eye. Use a "windshield wiper" motion lifting your brush as little as possible. Follow the natural contour of the eye and blend up and out. You may wish to bring the color onto the outer corner of the eyelid a bit too, creating a sideways "V." Some wonderful makeup brushes to try include the Eye Shader Brush and Crease Brush for a softer look; or the Eye Contour Brush for more drama. Sometimes I use a lighter shade in the crease, sometimes darker, sometimes shimmer, sometimes matte. Don't be afraid to experiment!