This eye shape is characterized by its lack of a (or a very small) crease. This might sound like a negative, but it also means there's more lid space to play with.
For this shape, apply a light shade of shadow across the entire lid. To create the illusion of a crease, apply a medium shade where the crease would be and blend. Line the upper lash line only in a dark shade to really define the eye.
Bonus tip: Blend the eyeliner upward to create more definition and open the eye. A light sweeping of a light, shimmery shade across the brow bone does this too.