Have you ever noticed that when you're reading an assignment from a textbook and you come across a thing that says, "The [blank] empire was built on these three principles. First..." you start highlighting beginning on "first?" Instead of saying that, it could say, "Goats are funny for three reasons. First..." and you would still highlight even though the relationship of goats to the [blank] empire is minimal. Point being that highlighting is more or less automatic, I think. You highlight more because of phrasing than because of content. Obviously, this isn't always true, but pay attention next time you're highlighting.
Also, you should check out this page right here. I bet you're wondering what it is. Well, this man name Dave Eggers wrote a book called "A Heartbreaking Work of Staggering Genius," which is a brilliant book and renewed my love for reading. Anyway, his book was just released in paperback and the New York Times did an article on it, here (note: you'll have to register for free with NYT to read it, if you haven't already). After Dave read the interview he wrote a long rebuttal/correction at mcsweeneys.net, which is the home of the literary journal, McSweeney's, who Eggers is the editor of. The reason this article is so good is because he posted the entire email communication between he and the journalist leading up to the article. It is amazing to see the change in tones and attitudes of both parties. It really gives you an insight into the world of journalism. I recommend everyone read it.