Previewing is especially useful for getting a general idea of heavy reading like long magazine of newspaper articles, business reports, and nonfiction books,
It can give you as much as half the comprehension in a little as one-tenth the time. For example, you should be able to preview eight or ten 100-page reports in an hour. After previewing, you’ll be able to decide which reports (or which parts of reports) are worth a closer look.
Here is how to preview: Read the entire first two paragraphs of whatever you’ve chosen. Next read only the first sentence of each successive paragraph. Then read the entire last two paragraphs.
Previewing doesn’t give you all the details. But it does keep you from spending time on things you don’t really want – or need – need to read. Notice that previewing gives you a quick, overall view of long, unfamiliar material. For short light reading there\s a better technique.