If you are a current or potential client, please stop reading at this time. Seriously. Go play on Pinterest or do something else productive. Once you are gone, I can tell everyone else a little secret about how to get some natural, fun shots of people. I can tell people that the secret is to lie. Tell subjects that you are just setting up your camera and testing the lighting when you first start a session or when you change locations. Then snap away. When people don't know the camera is really working, you can get some honest images of people like the one below.
Please visit Leslie at Week by Week to see how she captured candid.