If you’re an actor, your headshot is your single most important marketing tool. If you want to be taken seriously by casting agents, and when it lands on that decision maker’s desk or computer monitor you want the reaction to be “Wow! Let’s see that person!”
When shooting headshots for actors, I often get the question “What are they supposed to look like?”  or “how do you know you are getting the best headshot?”
The simple answer is… the best headshot for you is the one that fits your style and the look you are achieving.  Headshots can be on black or white backgrounds, and in natural or studio light. The standard white backdrop is gradually being replaced with a cinematic outdoor (but well-lit) setting, but both are acceptable as long as the image highlights YOU.  The focal point here is your personality. As long as you are not upstaged by a busy background the setting is not as important as the quality of the photograph and its ability to present the image you want.
Yes, there are some rules when it comes to actor headshots – and these fluctuate according to the type of work you are trying to get – stage, commercial, TV drama, etc.  Do some research in the field for which you are auditioning and make sure the technical details are there (print vs. file, cropping, etc). Bring all this to your photographer and make sure you leave your session with what you need.
Christian Webb,  a renowned NYC Headshot photographers points out what I believe is the most important criteria for selecting a photographer for you actor headshot, “…make sure that the photographer is actually BEST for you regarding comfortability.  When searching for someone to shoot your headshots, it’s important to get a sense of the photographer’s personality and their way of working.  Checking referrals,  reading their info on their website,  asking around from others who have shot with them before can help in making the decision as to whether a particular photographer is BEST for YOU to work with.”
Because ultimately, you want to be comfortable in your session. After all, you may be living with this shot for quite a while and you want it to showcase you and your ability.
When I photograph actors I discuss the type of roles they are going for, whether they are looking for the commercial “I can sell cereal and cars” image or you want that big part in a then next hit Netflix mystery drama.

A headshot session should be a fun, collaborative process with your photographer. Killer images will make the casting agents stop for just that extra second to pause and consider your image.