I'm not a professional genealogist. I believe I've said it before but I'll say it again and I'll continue to say it; I'm a family historian. I am, however, a professional librarian with decades of library experience and decades of family history research experience. I've made many of the mistakes that most people make when they start researching their family history.
It's good to begin with a goal in mind. Maybe there's a family illness that you want to get more information about. Maybe there was some change in the way your family lived and you want to understand what changed. Maybe, as in my case, there's a family legend that you've grown up with and you suddenly realize that you have no idea if it's true or not. And, maybe you just want to know more about the people who came before you. It's good to begin with a goal in mind to aim for.
But, sometimes the desire to reach that goal makes us impatient and sloppy and we leap on the first new clue that seems to move us closer to that goal. Sometimes, too intense a focus on that goal leads us to overlook information that initially seems unimportant and trivial because it doesn't tell us anything about what we're so intent on finding. That can be a mistake that will cost months and years of time in backtracking to recover information we bypassed and ignored.
I began with a very specific goal and spent quite a few years moving along fruitfully toward that goal, in a straight line and up against a brick wall in my matrilineal family. Along the way, I noticed other interesting things about other branches of the family and learned some things about my paternal families. I decided to research ALL my families, maternal and paternal. After years of research, having reached brick walls on every line, I realized I need more living relatives to tell me what they know and, since I'm not getting any younger, neither are they and time is a-wasting.
There are too many gaps in too many family branches; decades are empty when I can't find a particular family group. Why? Where were they?
So, I began a Cradle to the Grave research on each and every individual in my database, to fill in holes, not just for that individual but for their parents, spouses and children; because you never now where a bit of information has been documented.