I wanted to share this tip after finally piecing together a matrilineal line. Don't forget to trace down those "unrelated" individuals on the census! My ancestor's husband had died within six years of her marriage, leaving her with two small children - and me with no idea of her maiden name. Her first name was too common to be of any use by itself, but the person she was living with finally solved the problem for me. In following the family from the 1860 census to 1870, I was able to identify the "boarder' in the house as the woman's brother.
With that information, I followed him back on the census. The census soon yielded their parents' names as well as the names of their siblings. A quick search of the Barbour Collection located her exact birth date and location. I went back three more generations that day. All because I finally decided to follow everyone in the household, not just the person I was sure was related to my ancestor.