Learn to read
"If you can't say it clearly, you don't understand it yourself." (John Searle)
The most important advantage of writing is that it helps us to confront ourselves when we do not understand something as well as we would like to believe.
"The principle is that you must not fool yourself, and you are the easiest person to fool," Feynman stressed in a speech to young scientists.
If we don't try to verify our understanding during our studies, we will happily enjoy the feeling of getting smarter and more knowledgeable while in reality staying as dumb as we were.
We have to choose between feeling smarter or becoming smarter.
Only the actual attempt to retrieve information will clearly show us if we have learned something or not.
While it is obvious that familiarity is not understanding, we have no chance of knowing whether we understand something or just believe we understand something until we test ourselves in some form. If we don't try to verify our understanding during our studies, we will happily enjoy the feeling of getting smarter and more knowledgeable while in reality staying as dumb as we were. This warm feeling disappears quickly when we try to explain what we read in our own words in writing.
We can only improve our learning if we test ourselves on our progress. Here, too, rereading or reviewing does not confront us with the things we haven't learned yet, although it makes us feel like we have.