The first thing you can do to prepare for your headshots is think about what kind of style you wish to achieve and always keep your casting type in mind whilst considering this. Practice your looks in the mirror so you know how slight changes to your expression can give a whole different look, you may feel strange at first but it'll make you feel so much more comfortable once you get in front of the camera. The biggest thing I recommend to clients who are coming for a shoot is to wear your hair and makeup the same or at least similar to how you would wear it for an audition, you want the casting director to have no doubt in his mind that you are the same person as your headshot, especially in crowded auditions! So don't go too crazy with the curlers as tempting as it may seem, as I mention in the full document you can always bring extra makeup, curlers and even a razor for the Men to use during the shoot and enhance different styles.