I would try different light locations. The right spots are dependent on how you want to light the model or landscape. I comes down to what looks best to you.
The three point light system is an old trick from before ambient occlusion. In Blender I use three point lighting often. One, off to the cameras side and in front of the primary objects for specular highlights. A second light over head, with out shadows, used for general illumination. The third I place behind the primary objects. This can be used for fill light, or more often casting dramatic shadows in front of the primary objects.