If you've got any older relatives, you already know that it's a good idea to interview them -- and as soon as possible. But if you're not quite sure how to get started, take a look at Capturing the Past (go to the "How To" tab and then select "Oral History"). Admittedly, it wasn't produced yesterday, so some of the equipment may look a little dated, but all the principles still apply and it's a terrific prep tool to make sure you're ready.
And by the way, for fans of Stephanie Ririe of Ancestors fame, you'll be happy to know that she's featured!