Lens flare can add a nice, buttery soft and warm summer feeling to your photos. To get lens flare make sure your camera is pointing directly towards the sun. (Note that this may be harder to achieve mid day when the sun is super high.) Have your family stand with the sun behind them or slightly to the side.
To get the OPTIMAL lens flare, shoot during "Magic Hour". Magic hour is the first hour when the sun rises and the last hour that the sun sets. See these examples of harnessing the lens flare technique: