One common mistake beginners make is not interviewing family members, the older ones especially.
Start with your oldest relative and set up an interview, if they live close by do it in person. Video tape it if possible. Have your questions written out before you get there. Don't just ask for names & dates include churches they belonged to organizations, employment, their favorite memory, what it was like growing up where they grew up. Have them show you old photo's, memorabilia.