WHAT SHOULD I WEAR FOR MY HEADSHOT?
Choose an outfit that you would wear when meeting one of your best clients.  If it is a suit, be sure the jacket fits well.  The camera blatantly shows if seams are straining, or if your shoulders are swimming in extra material.  Choose a solid color that is somewhat darker than your natural skin tone.  A deep red, gray, green, brown or blue suit jacket is a good choice, as these colors look well in both black and white and color. Under the jacket you can wear a contrasting top with a simple collar such as a jewel neck or traditional shirt collar.  Avoid ruffles, fussy or plunging necklines.  If you are not wearing a jacket, avoid tops that are white, pastel, patterned, striped or with bold prints.  They draw the eye to the clothing instead of the face. Simple, non distracting jewelry, such as stud earrings or a thin necklace, will give you a professional look. In general, avoid dangly earrings, unless they are an integral part of your "look."

WHAT ABOUT MAKEUP AND HAIR?
Even if you don't normally wear makeup, it's best to wear it for your photo session.  Use a concealer to minimize blemishes and uneven skin tone.  Wear eye liner and mascara to make your eyes stand out but don't over do it.  Use soft and neutral blush, eye shadow and lipstick colors.  By all means, bring powder to touch up shiny areas. Everyone should use a bit of hair spray on windy days.  It is usually not a good idea to try a new hairstyle for a photo session.  If you want to experiment with a new style or color, you may want to get accustomed to it before your photo session. 
Bring your comb and brush, hair pins and other fasteners for the session.