Before doing any portrait photography there are some very important questions that any photographer should ask himself. What kind of light source it's going to be used? From what angle the light will fall on the subject? What film, camera and lens are best to use? If you manage to answer all this questions before taking the photo then you will probably make quite a good portrait photography. But i know that you don't want a good portrait photography, you want a perfect one. So the best way to achieve this performance is to talk with the client trying to know him, his past, his desires. This way you can create distinctive portraits. If you want a real great portrait then you have to add a bit of the client's personality in the photo. This works very well especially when you make female portrait photography. You shouldn't look for a face that is over painted by a makeup artist. Try to surprise something that really represents the subject. If you are wondering what to talk about with your clients then the answer is anything that will show you something distinctive for that person. Try to look for different face expressions and eye or mouth movement. When you see something beautiful keep it in mind and later capture it in your portraits. Belive me that studying the subject before making the portrait photography is the biggest secret in this art. Meeting with the client, building rapport, knowing the client, and planning the session are essential elements. So don't do the final session at the first meeting. After you are sure that you know everything you need to know to make a perfect portrait photography choose the best location and time of day and take the session. I advice you to always use natural light if it's possible. Choosing the background it's also very important too. If the picture is to close then the background looses any meaning, if it's to far then the background will overwhelm the subject. So try not to merge the subject with the background in an indistinguishable shape. From my point of view making portrait photography is the greatest art. I believe this because it's very different from making landscape photography or nature photography. When you make a photo you can make the subject to react to your wills and you really can control the picture.