Prior to becoming a Photographer I was a Headhunter. Basically employers would hire me to find their next super-duper Rockstar employee. To do this I would have to look through hundreds of applicants, screening them for skill set, talking to them for soft skill set, prepping them for interviews etc. One of the areas I coached was presentation and branding, both online and in-person. Let me dig a little deeper...!
You see we are visual people. Take a situation where you meet someone for the first time face to face. Instinctively you look for micro expressions, in that 1 to 2 seconds you are searching for a connection at a subconscious level. Have you ever met someone that just didn't feel right? That is your subconscious telling you that the micro expression hunt came up with nothing, so you just can't connect with the other person. The EXACT same thing applies to your online Branding, be it through your LinkedIn page, informative Twitter account, vibrant Instagram page, jam packed GitHub, Your headshot is front and center of that experience!
An amazing headshot shows that you are Professional and Confident while being balanced with warmth that shows you are Approachable. Confidence lives in the eyes and approachability comes from the mouth. Here is an example:
Remember as a job seeker you are your own brand! You have to market yourself to get the word out that you are awesome! Use your headshot to show who you are... a Confident, Approachable and Professional person!