A dark, smoky outer corner of the eye lid is hugely popular right now. Not only does it add depth, but it can create an instant eye lift. But it's tricky to master. My top three tips are to make sure the eye shadow you use is dark enough, to blend well using a clean bush, and to practice.
When it comes to application, make sure to use a small enough brush, smudge the color into a V on the outer corner, then tap the color to fill in the V. Finally, blend the color inward with a clean brush. If the color isn't dark enough, add more. And if you blended the color in too much, just take a different brush with a pale color and sweep from the inner corner toward the outer corner.
Since it's difficult to explain, check out the video below for a demonstration.
For another take, as well as a phenomenal tutorial for those with hooded eyelids, click HERE for a demo by Wayne Goss.