Years ago I did a tree on Ancestry. To start with I had a typewritten list prepared by an uncle so I could check to make sure I was getting the right story each time.
I followed the male line back to the first of my name in North America, a ferry operator in Connecticut. Then as I started considering my mother's side, Ancestry came up with a special weekend search your British ancesters for free offer. So I continued our male family name using the British archives. They have church records going way back. In my case all the way to the first of my name in 1066. Turns out the founder of our line was an Anglo-Saxon turncoat that let the Normans into the local Castle. He was rewarded with a property and a name - the first 'earl' of [our family name] - or "laird" is probably a better title (it was close to today's Scottish border).
I'm not 100% confident that the records can be trusted that far back, but the indication was that that my first named ancestor was the second son of the local King and it was a bit of sibling rivalry that turned him to a traitor. Whatever, the family lost the 3rd generation to a horse riding accident, and the 5th generation (I think) to a burning at the stake after the local populace got sick of his predatory paedophilia. The family lost the "laird-ship" to another family that had been close allies for years. Coincidentally, my dad grew up with his best friend who was himself a descendant from that family that replaced ours as "lairds".
I never did get very far on my Mother's side. I've got a photo with 5 generations of women in it, my sister being the youngest. So I've got the starting point for that one. But I only think I got 2 or 3 generations past that. And of course you have to decide which line to follow back at each point, father or mother.
EDIT:
this is a hijack. Do we have an 'Ancestry' thread? I should move this there.