I was fortunate to be able to piggy-back on research done by various cousins on both sides of the family, and while there are a few brick walls, I have been able to trace the various lines back well beyond their arrival in the Americas in the 17th and 18th centuries (there was one on the first boat to Jamestown in 1607, and several on the Mayflower).

A free site that I've found useful that gives you access to others research is www.rootsweb.com. Once you have put in your ancestor's name (I find it good to put in the next to oldest in the line) if there is a finding in Worldconnect, click on that. You can then narrow down the results using spouse name, parents, dates, etc. I've found this very useful in extending my tree.