Well, it always works if you could go through the textbook some time and jot down the keywords or key points that make you easier to do review. So you don't have to slog through the reading multiple times. To ensure you understand the content or theory, test yourself by answering the questions at the end of the chapter. Besides that, be sure to do all the sample exams or previous papers under timed conditions. It is critical that you spend the time to figure out and understand the correct answers of the questions you get wrong. You could re-read the information in your textbook if you still struggle with particular topics or concepts.