taken from; http://www.suite101.com/article.cfm/acting_real_world/81541
I wrote in the last article about knowing what you're going for. Even when you know this, it's easy to get sidetracked looking at really great-looking photos without considering what those photos "say" about you. I basically follow a process of elimination. Any photo that downright sucks (technically or for any other reason) is struck from my list, leaving me to start narrowing down choices based on merit. From there, the first pictures to go are the ones that aren't fully "present" (maybe the shot went off just a hair after the peak moment) and the ones that are "pushed" in an obvious way. You want pictures that look natural and full of life. Once I narrow down to just these pictures, I start eliminating photos that are too generic. I have one comment I'm looking at now that says, "nice guy, but who is he?"
If you're a character actor, your picture should be very specific, so that the casting director will see it and say "this guy is totally a mechanic," or "that woman is a perfect news anchor." You will have thought about that before you even shot your pictures, and your wardrobe and session on the shooting day would have all been geared toward getting you a number of those types of photos. If you're a leading type, it's actually harder. A lot of leading types simply pick the picture that looks best, but that's not going to help. If your picture draws a blank when the casting director shuffles through a stack of submissions, they'll keep shuffling past you. Your picture still needs to be specific. Is there a thought behind your eyes, something that engages the viewer? Does that thought send you into a quirky, James Spader direction, or does it send you into a more heroic, Arnold Schwarzeneggar direction? Be realistic about what your type is, and choose the photo that best captures the spirit of what you have to offer. Ideally, you'll walk in the door looking and acting exactly the way the headshot represented you when the casting director first saw it and decided to call you in.
here is my favorite headshot from one of my facebook buddies. I think its an exemplary example. Not my photographer because this photographer is extra expensive. The actress in this photo is Gillian Glasco.