If this is dynamic hair, you could increase the density. If you increase it too much, the hair starts looking plastic so don't overdo it. It also helps to set the hair material to "opaque in shadow" in the material room.

Poser 11 Pro, Windows 10

Auxiliary Apps: Blender 2.79, Vue Complete 2016, Genetica 4 Pro, Gliftex 11 Pro, CorelDraw Suite X6, Comic Life 2, Project Dogwaffle Howler 8, Stitch Witch