Before we create any kind of lighting setup in the scene, we need to first of all create our definition or vision regarding what we want to accomplish in our final render(s). At the risk of starting to sound a little repetitive, it is important that we get this created so that it can serve as the guide or blueprint that we use as we move through creating this somewhat different lighting setup.
Now, while a definition created entirely from our own imagination can be used as a blueprint for our scene, it isn't generally speaking the best way to go about creating a document that, as we have noted a few times already, is fairly important with regards to the success of the project.
Even if we are working at creating a completely fantastical lighting setup—something that doesn't exist in the real world—we still need to create it based on the reality of how light works. The behavior of light is something that those who view our images will be incredibly familiar...