Cameras are used to photograph people more than any other subject. The main shortcoming of many of these images is that they rarely capture more than a physical likeness. To improve your portraits read on.
For more formal portraits do not use direct camera flash as the light will cause harsh shadows and often produces red-eye. Soft natural daylight will be a much better choice. The eyes are the most important part of a portrait, so always make sure they are in sharp focus. A small dose of fill-in flash can give a nice sparkle to the eyes. A large aperture will throw the background out of focus and direct attention to your subject. Since not everyone feels naturally at ease in front of a camera, chatting to them wil make them forget the camera. A short telephoto will avoid distortion and helps to keep a comfortable working distance to make it less intimidating. For intimate candid portraits show something of the person's surroundings by using a standard lens or wide-angle. Keep your camera ready and react to situations quickly and unobtrusively.
Kids tend to be quite natural in front of a camera. However they have a short attention span, so keep sessions short and interesting for them. Follow them around with your camera and use your tele zoom for natural candids. One last tip, try black & white for a change.