There are several ways to do this. One way is to take lots of photos. These photos I present below are from a group of about 60 shots. As you can see, of those 60 shots I took, only about 3 or 4 are worth keeping. This is pretty typical. If you are shooting digitally, taking lots of photos is not going to cost you anything, and it's worth doing no matter what the subject, but is especially essential when shooting portraits. Another technique that is often used by photographers to get their subjects to relax and forget that the camera is there is to engage them in conversation. I usually do a combination of both. You have to be careful with the conversation, however, because if you snap a photo of your subject while they are talking, then you might capture them with their mouth open. Plan on taking one shot after the other- that way you'll get some good ones during conversation pauses, or even better, when your subject is laughing. It's always good if you can get your subject to laugh.
This set of portraits below are of my sister. I have one sister and she is three years younger than me. We've always been close, growing up and now that we are adults. However, just because I have a good relationship with her doesn't necessarily mean that I can take a good portrait of her. She's always presented a challenge to me photographically. She's an attractive woman, but we tend to cheese it up when we are around each other, so my portraits of her are often stiff. She doesn't look at ease in front of the camera, and her smiles don't always look natural.
(Captions refer to the photo above) I think this was the best shot of the group, because I managed to trip the shutter when she was laughing. This is how she really smiles and the look on her face is relaxed, open and natural. However, her face is in shadow a little bit, and when I looked closely at the photo, the focus on her face is not as sharp as I would have liked. You have to watch your camera when taking these types of shots. Sometimes the autofocus does not focus on the elements of the photograph that you want it to focus on. Often, you don't find this out until the shoot is over and you're viewing the photos on the computer screen. That's another reason to take several different shots of the same pose. Chances are one of them will turn out the way you want it to.
In some ways, I like this shot more than the above shot where she is smiling more. The light is better overall, and the angle of the photo is more interesting. She's not looking directly at the camera, which might bother some people, but I don't mind it. It looks like she is contemplating something.
Usually you never want to undershoot (placing yourself lower to the ground than your subject, causing you to have to point the camera up to take the shot) when taking portraits, because it is not a flattering angle for anyone. I sort of did that here, but I liked the resulting angle. The portrait probably would have been a little stronger had I not undershot it quite as much, but it was salvagable.
When working with people, you have to watch the expression on their face in each shot. This is much easier to do now with digital photography. As you photograph your subject, take the time to review the photo on your camera's LCD screen. Make sure they have their eyes open and mouth closed. Eyes closing in portraits is probably the most typical thing that will botch a portrait. Take many shots of the same pose in sucession (even use the continuous mode on your camera) to make sure you'll get a few shots where they eyes are open and your subject is looking good.
Sometimes portraits end up looking too serious. That's fine if what you're going for is a serious "artsy" or documentary photo. However, if the object of the portrait session is to get some nice relaxed photos of your subject that give off a warm, happy vibe, you don't want them to look like this. When reviewing photos as you shoot them on your camera's LCD screen, also watch for the mood that your sujbect's expression conveys. Make sure it captures the look that you want.
If you're shooting with film, it's a little more difficult to monitor how your portraits are looking as you shoot them. You really have no way of knowing until after the film is processed. We are spoiled in the digital age by not having to worry about this as much anymore, but there was a day not too long ago where all photographers had to combat this problem. The solution to this is just to take lots of photos.
