It is mainly a case looking to see the main words. Predominant clues are Bold Heading, chapter headings. Words in italics, underlined and just word that seem to appear a lot if you happen to notice it within the text. You're just trying to get the general feel of a book/article when you preview so that you can better state your purpose.
Know your purpose is the best approach to an article. What do you want to know. Do a quick preview and then check again... you feel you want to know what the article contains...is it important to you. 4 pages or more a photoread and then activate method could be the fastest way to go. With less, you could find all the information you need with a superread/rapid read method alone is a fast enough approach.
Alex
