WARNING: The most recent version of DAZ Studio breaks Ghost Lights, both purchased products and the home made ones described below.
Lighting DAZ Studio is a complicated subject. I am only going to talk about Iray lighting. Before Iray I did 3Delight renders and knew a lot about lighting for 3Delight, but I have forgotten most of it since Iray came out. Lights in Iray behave much more like lights in the real world than 3Delight lights do.
I am sure there are lots of people that know more than I do abut Iray lighting. I am only trying to cover the basics of lighting and I will not get into any advanced topics or special effects.
There are no right and wrong ways to do lighting. If you are happy with the way the render looks, then that was good lighting. There are also many ways to achieve similar results. How you want to do lighting depends on how you want the render to look and what kind of resources you have.
There three kinds of Iray lights in DAZ Studio.
1) Environment