How to grasp the main idea rapidly and accurately when reading?
1) Make sure you understand what the general theme of the text is. (Look at the title, headline or headlines.)
2) Scan the whole text quickly. This means running your eyes down each page to get the general theme of each paragraph.
3) Skim-read the text paragraph by paragraph. This means looking hard at each paragraph in turn, concentrating mainly on verbs in order to get the topic of each paragraph. Skip examples which simply illustrate the theme. Only read selected sentences in detail. It’s up to you to make the best choice of sentence.
4) Make a quick note of what you think you have understood.
You need to train yourself to carry out these steps. Practise the steps over a period and test yourself by going back and re-reading the text carefully. Then see whether your notes are accurate until you have confidence in using speed-reading techniques.