Go Unposed: Not only can you get good smiles and good shots out of unposed pictures, but shooting while the subjects are unaware might lead you to an even better portrait. Shoot before and after the "posed" shots to catch more natural expressions and interactions.
Shoot from Above: Try shooting from above the group. When they look up to see you, each person’s face will be visible and the angle will be flattering.
Arrange People in Levels: Create a more dynamic shot by arranging everyone so their eyes are at a different level. Eyes draw you in to a photo and by having them on different planes you'll guarantee a dynamic shot.
Bring People Together: In this situation, asking the subjects to put their arms around each other helped close a gap between them. It can also guarantee smiles as subjects play off each other's energy.
Form a Visual Triangle: When arranging groups, avoid static-looking rows. Creating a triangle formation gives the shot a sense of unity.
Capture the Kids with Ease: When photographing a group of kids, take photos during play rather than forcing posed shots. By simply asking them to turn to the camera you can grab great personality shots with lots of impact without sacrificing the kids’ playtime.
Place Your Subjects with Purpose: Assemble your group and personally place everyone where you want them to stand. If someone is wearing brighter clothing, you may want to place that person behind other people or toward the center so that he is not as distracting. Important family members, such as grandparents, should be situated in the center of the group.
Place People on Levels: Placing your subjects on different levels increases the interest in any group photo. Use natural or architectural elements to do this outdoors. Let everyone do what’s comfortable, whether it’s standing or sitting or jumping on someone’s shoulders to get the effect.