Often information that seems important when you first read it does not turn out to be so important after you have read the entire section. Do not underline or highlight too much. If you underline everything it is just as useless as underlining nothing. Make the major points stand out clearly. You can develop special markings to use on major points so they are set apart from other information.
Many students find that making notes in the margins of their book while reading is very helpful.
This is often more convenient than making notes on a separate piece of paper. This method also makes it easier to refer to information in the book while using your notes.