The key to informal portraits is to understand that sitters are likely to be nervous or self-conscious. Keep these tips in mind to get natural, relaxed portraits:
1. Get the light right. Start by placing your sitter in good light- for example, next to a window that is not in direct sunlight. This light is not too harsh and allows shadows to define features. Move closer as they grow more relaxed.
2. Give them something to do. Your sitter will be more relaxed if they have something t do with their hands, such as holding a drink, or a tool of their trade, rather than trying to strike a pose. Keep chatting and taking photos the whole time.
3. Share the results. Show your subject some of your shots so they can see what you are trying to achieve.
4. Keep shooting. Take lots of pictures to help them grow more confident in front of the camera, and to catch the elusive expression that best encapsulates their character.
5. Focus on the eye. Make sure that the closest eye is sharply in focus. The rest of the image can be slightly unsharp and still be OK.
Adapted from How To Photograph Absolutely Everything: Successful Pictures From Your Digital Camera by Tom Ang (DK Publishing, 2007, $40)