With the light on the model's face to perfection, there's still a lot that can be done in high key, low key, and all the exposures in between.
When starting out using strobes, the important area to master is the overall exposure of the subject. Then you start to add in the scene as well, with a background light or complex cross lighting. But one light I personally love to see is a hair light. Usually these lights are either directly behind the subject, or off camera at an angle to the right or left of the background. There is so much value top be had out of these.
Gary Fong's Instagram post above — shot by Steven Scagnelli — is one of the best examples of just how much impact it can have. Not only does it give superb separation of subject from background, but it adds a cinematic quality that all back-lit images seem have. The color gel added in the above image just takes it that little bit further.
Do you use hair lights? Show us some examples in the comments.