"Mary L. B." has placed an interesting article on the EOGN Discussion Forum that I wish all genealogy newcomers would read. Entitled, "Pitfalls That Can Create Brick Walls or Cause You to Claim the Wrong Ancestors," Mary details several bits of "misinformation" that most of us struggled with when we first started.
The article describes the confusion over the terms Junior and Senior in old records, the relationships of children in a household in U.S. census records, marriage licenses versus marriage returns, and more.
You can read her excellent article at: http://www.eogn.com/forum/index.php/topic,242.0.