Where I started was in the present. Make sure you can account for the name and location of all of your living family members. Go backwards from there, making sure that you talk to the oldest people first. I learned a lot by sending off for birth/death certificates and Social Security applications. The Ancestry.com site has more and more useful databases. Be prepared for it to take a very long time. But it's also fun and you sometimes feel a spiritual closeness with ancestors you never knew. I decided to do this to honor my great-grandmother Maggie, who was a slave, and those before her.