For Alexandra Sherman, who's 8 years old, just about every holiday has a do-good component. On Thanksgiving, she and her family prepare food and set tables at a nearby soup kitchen. On Christmas, she helps deliver meals to homebound senior citizens. And on her birthday, she chooses one gift to donate to a local charity. "Alex is an extraordinarily lucky kid," says her mom, Melanie, of New York City. "She comes from a family who loves her and can afford to give her many great things, but there are plenty of families who don't have a lot, and I want her to feel it's her responsibility to give back." Indeed, it turns out that 7 to 8 is a great age for kids to start volunteering, and there are simple ways you can help your child get the most out of the experience.