There are many ways to light and pose a headshot. More contemporary looks – and my current approach – is to keep them light and bright, with either paper white or light gray backgrounds.
The key to a successful headshot is the subject’s interaction with the viewer. To achieve this I believe in direct eye contact. The subject must also be engaged from a personality perspective as well.
Following that is the pose and the lighting.
I try to follow classic posing cues: soft, sides of hands (if present), non-straight lines and triangular compositions. Albeit with a modern twist. This isn’t really a portrait, so we walk a fine line between the formality of one and the informal, direct nature that is emblematic of the contemporary headshot.
As for lighting, I’ve begun to embrace very large specular sources (which turn out not to be so specular due to the apparent size to the subject). Again, this is a nod to not only the informality of the shot but also to my beauty photography influences and background. That large source is fairly flat, but due to the modifier I use drops off quickly (it is a parabolic). It is also very forgiving and works with a variety of age groups (whereas my other favorite, the beauty dish, lends itself to younger skin). It is also not very fussy in terms of subject positioning relative to it, so a variety of poses can be attained without having to change the lighting setup.
I see the headshot as essentially a tool – a tool to use to get you noticed. It needs to resemble more of a glamour/beauty/magazine ad than a formal portrait. It should be light and bright to draw the eye. And engaging to draw the viewer in to remember the subject – to get you noticed.