I highly recommend taking the time, periodically, to go back through your family files, folders, and notes. You never know what little gem might be hiding right under your nose! It will give you the opportunity to re-familiarize yourself with "long neglected" ancestors. There is also the advantage of double-checking source citations for the facts you have entered into your genealogy computer program.
I have spent most of the last three or four months digging through my family folders to make sure my facts had source citations, rewriting biographical sketches, checking the internet for new data, and double-checking sources to see if I had missed anything the last time through the documents.
You might be amazed what you missed! A second, third, or even fifth look at those piles of papers you have stacked up on the dining room table might just hold the keys to unlock long unresolved mysteries.
Census Records: You might find that you missed a relative or two on page 2B when your 3rd great-grandparents' clan was on page 2A. A married daughter might turn up on the list, now that you have located her marriage record, and she was the one who took in Grandma. The 1900 census might reveal that your great-grandparents had three children, but only two were living at the time. That narrows the search for Great-Uncle Billy. Perhaps you missed the year of immigration for an immigrant ancestor.
Military and Pension Files: Going back through military records or pension files might turn up a family connection, birth, or event that you had previously overlooked. A review of county histories might give you a clue to where to look for a needed record. Maybe a name that keeps popping up as a neighbor to your Revolutionary War ancestor will appear as a member of his regiment and lead to new information.
Family Group Records: You may also find that you have conflicting details on a birth, marriage, or death record for an ancestor. Perhaps another paper in that family file will confirm one of the dates. You might decide after examining a family group sheet that Aunt Bertie wasn't your father's sister, but his great-aunt.
Birth, Death, and Marriage Records: Take a look at the witnesses and dates; you may have missed something, someplace, or someone. I had a marriage entered with no source and could no locate the source in my records. An internet search for the spouses led me to the Henry Co., Missouri GenWeb page. There I found an obituary for the wife, death and burial information for the couple, plus other goodies. Some mistakes (not citing a source) can lead to a cache of genealogical gems!
Obituaries: Go back and reread the obits for little gems you might have overlooked. My grandmother's father had two brothers and a sister. Great-Grandpa and his brothers made things relatively easy. They married sisters. Great-Grandpa's sister was another story. I had her first name, but that was it. As I reviewed my "Alpha-Omega Album" (birth, marriage, and death certificates and photos – mostly of gravestones, but also a few family pictures), I reread the obituary of my great-grandfather. There was his sister's married name. From there I was able to find her marriage and glean a few details from the census records.
City Directories: Clues to employment, family relationships, and residences abound in these treasure chests. The directories may also solve other mysteries. Staying with the same family from above, the marriage of one of Great-Grandpa's sisters-in-law was a bit of a mystery. She was listed as the wife of Albert Faucett in the records, but I couldn't find his death or ties to my Faucetts anywhere. I revisited the Indianapolis City Directories. She was listed as the widow of Albert, Alfred, and Alpheus in different years. Ah-ha! Alpheus was Great-Grandpa's brother. That verified the three brothers marrying three sisters. It was the second marriage for Alpheus.
County Histories and Compiled Records: Make sure you look through the information on all of the related families, as well as your own surname. There might be a mention of the 5th great-grandmother in a bio of her sister. Tax records might turn up a spelling variation. I spent several weeks putting together migration trails and locating spouses for my dad's grandfather's siblings. I was able to find all but one, the eldest brother. His wife had been previously identified as Anne E. Jones from the 1860 York Co., Pennsylvania Census. Other census records showed her as Anna M. As it turned out, Anne E. Jones was his recently widowed sister. I was going through a genealogy report published (1950) by the Historical Society of York County on the Prowell family, a copy that I have for about ten years. The report includes a few highlighted Prall items--one of which I had overlooked. On page 10: "James C. Prall, Ohio, and Annie Maria Hengst, York County were married 15 Sept 1865." There was a member of the Hengst family living with James and Anna Prall in 1900. Another mystery solved.
Deeds, Mortgages, Probate Files, Court Records: Clues to a maiden name, lists of siblings, parent-child relationships abound in these records. Study them well! I was able to prove the link between my 6th and 7th great-grandfathers using mostly deeds, mortgages, and court records in Hunterdon County, New Jersey.
As you conduct your research, don't neglect the material you have already compiled. There just might be one or two interesting items buried in there just waiting for you to unearth them! You might take that mystery family back another three or four generations.