It all started in 2006, when I had just published my first genealogy book and I wasn't sure what to do next. Then I went on a dream trip, researching my ancestors in England, Scotland and Ireland. I mostly looked for the Thomas English family, Quakers that moved from England to Ireland and eventually to America. I started with information from Mildred Collier's wonderful book on Thomas' descendants. I wanted to find the primary (original) sources, look for ancestors on the female branches of the family, and learn some local history that might be useful in a future book.
I found most of what I was looking for, and more! Several of my direct ancestors died young, which didn't give me much material for stories. When I got home and looked through everything, I realized that their siblings and in-laws had more interesting lives. Some of the brothers-in-law — like John Clibborn — had done so much they even had local history books written about them!
My definitions: An amateur genealogist tries to see how far back they can go and only looks for direct ancestors. A serious genealogist is interested in siblings and related lines and writes down all her sources. An advanced genealogist is interested in the whole town or village, and writes down the sources of sources — and becomes a historian.