There are a variety of ways to do skimming (reading very quickly and generally to gain a broad overview of the reading content), and they can depend a lot on one's personal reading style/preferences and broader language ability. For example, one of the things that inhibits skimming for second language learners is an entrenched habit of trying to translate words and terms from English (the second language) into their own language, feeling this is necessary for precise understanding.
Here is one quick tip on how you might like to try and improve your ability to "skim" while you are examining a reading text. Look at the text image with colorful arrows drawn across it below. I can this approach the "Reverse Z-Skim", because it basically involves drawing your eyes across a paragraph to form a general reverse "Z" shape.
Start by reading the first sentence of the paragraph, relatively carefully (following the pink arrow on the image below), left to right. The first sentence is often very important and provides the broader framework of all the details that will follow (but not in all cases!). This is the top (and first) section of your reverse Z skim.
Next, allow your eyes to wander over the paragraph in a downward, diagonal direction from top left to bottom right (following the green arrow in the diagram below). As your eyes make this movement, allow yourself to notice the phrases and words, in small chunks, moving from top left to bottom right. Although you are missing many words in the paragraph, you are essentially taking in the "meat" of the paragraph, which all other parts connect to in some way. You shouldn't try to analyze this information ~ just take it in to give yourself an impression of it. Later, when scanning, you can look and analyze in more detail.
Finally, complete the bottom section of your reverse Z by reading (left to right) the final sentence in the paragraph ~ following the blue arrow. This sentence will often wrap up the paragraph in some way, and show you where the paragraph has ended up (compared to the initial sentence at the top of the paragraph). Just to reinforce this, you may like to re-read the first sentence again (at the top of the paragraph).
I use this method myself when reading, and have taught it to hundreds of learners. It appears to be quite effective ~ and it's fast, which is exactly what you need for longer texts and test situations.
Try it out and let me know how you get on!
