When developing traditions, families should look to the past to inform the future. Bring back old traditions by talking with family elders -- parents, grandparents and older aunts and uncles -- about the special things they did as children and young adults, then continue the ones that you like in your own family.
Part of creating a family identity is acknowledging the individual identity of each member of the family. Not all the old traditions you dig up will work for your family at present. Families should also create new traditions that will keep everyone interested and actively involved.
One way to build tradition is to create special family behaviors; things that the family does only with each other. A unique holiday gift exchange, family birthday celebrations and milestone traditions (a special dinner when a teenager gets his driver's license or an annual beach trip on the first day of summer, for example) are common family behaviors.
Holidays also lend themselves to creating tradition. Annual religious observances are usually marked in special ways -- family Christmas tree shopping and decorating, Passover Seder dinners, Easter Egg hunts -- that celebrate both holiday and family. You don't need a special occasion to create a tradition, however. A family can develop unorthodox traditions based on its own quirks, such as annually living like a tourist in your hometown for a weekend.
Whatever the new tradition, it's important to make sure that all family members are involved in creating it. This is mainly to ensure the tradition is something everyone will enjoy celebrating, but also that it reflects the family's distinct character. And the more enjoyment your family gets from it, the longer the tradition will last, possibly carrying over into future generations.