Instead of using concealer only underneath your eyes, use it on top of your eyelids as well. Why the hell would you do this? I'll tell you why.

It keeps your whole eye area (under and above) the same colour and keeps it all the same kind of smooth.
It acts as a primer and lets your eye shadow stay on way longer.
It brightens up your eyelid area so that if you do wear any eye shadow, it'll stand out even more.

I just learned to do this recently and have noticed a difference. Subtle difference, but a difference. Also, it really does help your makeup stay on longer. That's the main reason I do it. Well, that reason and the fact that I don't use eye shadow primers. (I totally would, but they're too expensive usually.)