In the case of my mother's family it was quite easy to start going back, her great grandfather wrote a family history and lineage for her grandfather so it is actually quite complete for part of the family. The book does mention that about 2/3 of the family tree was Puritan and the other 1/3 is Pilgrim, the author only covered the Pilgrim part of it. But it gave me plenty to start on up the tree using Ancestry and so far there are parts that I've gotten all the way back to 1030AD. On my father's side (still alive but I have no communication with him) there's some questions. For starters I don't really know who his father is. My mom thinks he may have been the product of a rape, she's not really sure and my grandmother doesn't talk about it. I haven't talked to her in probably 15 years, she's quite insane. Even if I could talk to her I wouldn't be able to get much information from her. While I'm not sure what his birth certificate might list if it shows anything that might be helpful. Though I'm not sure I can easily request a birth certificate of a living person for obvious identity theft reasons.
My mom's side will be very easy and there are so many great stories on that side (John Hancock, William Bradford, Thomas Paine, Robert Treat Paine, etc) that it will definitely be an adventure. My father's side might not have any great names but it would be cool to find out more about it, hell I don't even know the nationality of his father or any clue on his name (first or last name).