Being photographed is not natural, especially if you are not used to it and it is being done in a studio setting. People naturally tense up. In addition to the photographer, there may also be other people there, such as hair and makeup artists. Then there are the lights, camera, etc., etc.
How do you relax under these conditions?
It is probably best to start with a prop, including being seated in a chair or coach, or if on location with something in the environment. I’ve made the mistake of starting against a cyc wall with people who are not used to being photographed; I found the transition is too difficult and the initial images rarely useful. It’s best to ease into the process, and being comfortable and having something to use as an aide to posing can help you relax and improve the chances of getting good images.
Bring a variety of outfits. This goes for men too. You can’t use what you leave at home. Have an idea of what you want to wear to help with the decision making process, but bring more than you need. Worse case is you never use it. This is preferable to needing it and not having it.
It is best to have clothing without strong patterns in it, especially for women. It depends, of course, on what the session is about. If there is a concept, discuss it with the photographer ahead of time. It is always good to bring black and/or white outfits or tops.
Consider a location portrait. Studio work in and of itself can be intimidating. Locations help by providing a familiar feeling.
Finally, what will make or break the photograph is your engagement with the camera. Your eyes provide the key. One of the reasons images with the subjects eyes closed work is because it removes this variable. Eye contact without engagement with the camera is deadly to an image. The viewer must be drawn in.
One of the tricks I have heard to achieving this is, for women, to practice your “makeup face.” You know, the relaxed, intense look when you are applying makeup and want to check your work. The different facial expressions that you use to make sure you looking good.
And “smile with your eyes.”
These are a couple of shots I took of Nancy, an elegant woman that I photographed lately in a portrait session in studio. I generally choose to do images with eyes closed in a soft, dreamy type atmosphere in addition to eye contact with camera. I found the images we did with her seated in a comfortable chair were the most successful of this session.