In putting together a timeline, I start with the basics: deaths, marriages, divorces and births in the immediate family. Then I add in other things like moves, wars, natural disasters and frankly anything I can think of that would have impacted the person in question. Some family tree programs now offer a timeline feature (Family Tree Maker and RootsMagic do) which can make this process easier. This is a good place to start, but can be limited by what you have typed into the appropriate spot in your genealogy software.
Once I have my timeline I try to imagine how I would feel if that series of events happened to me. A parent may have died within a few years of a grandparent or sibling. Maybe there was a divorce, re-marriage or the family moved. Put it all together and it can change how you perceive that person and their life choices. As an example I'll use my grandmother's sister, Mildred. Perhaps the most notable feature of her short life was her dramatic death. Mildred was shot through the window in the wee hours of Christmas morning while preparing gifts for her children. This is what I was thinking about when I began to write about her, but I realized that there was much more to her life than her tragic end.
Mildred's life started out pretty well. Unfortunately, everything changed with her father's death when she was only ten. Her mother then moved from Ohio to Kalamazoo taking Mildred and her four siblings away from the only family they had really known. Now they watched their grandmother die six months after their father had. Meanwhile their mother struggled to put food on the table. Mildred became sick with tuberculosis and was treated in the Kalamazoo tuberculosis sanitorium. She recovered, married, had children and separated during the same time her mother remarried (twice) and the rest of her siblings went their separate ways. As if that weren't enough, this all transpired during the height of the Depression. This fateful period was apparently when Mildred met her new boyfriend, a boxer and petty criminal who ultimately murdered her in cold blood on Christmas. In the end, Joseph Salpatrick freely walked the streets of Kalamazoo for close to thirty years after Mildred's death (but that's another story). Read Christmas Morning Murderer Gets Off Easy for more and Christmas Morning Murderer Pt. 2 Pt. 2 to read how Salpatrick got off.
From the moment Mildred's father died until her own untimely demise not twenty years later Mildred's life was unsettled at best. The remainder of Mildred's childhood would have been difficult. Her early twenties would have been no better. While in the sanitorium she would have been physically separated from her family. Once she got out, life in her mother's household was likely chaotic between her marriage and children, her mother's love life and her siblings marrying and moving out. Considering the many changes in her immediate family I would not be surprised if her support network was at least a bit tattered (and no one had cell phones to easily keep in touch). Given her dead father and failed marriage Mildred may have been a little desperate for male attention. All of this likely made her more vulnerable to the apparently charismatic Salpatrick.
Until I laid out all of the pieces and put them together I never really understood how difficult Mildred's life was, even before the events that led to her murder on Christmas. Keep in mind that I had no journals or family stories to put this together. My synopsis comes from census and vital records, city directories and just a few tidbits from a couple of other sources. I hope this provides you with a good example of why I believe building timelines can be very beneficial for gaining a better understanding of our ancestors. I encourage you to start with a person you have always wondered about. This relatively simple task may teach you something new.