In order to study more efficiently and retain information, I would suggest that you adjust your usual methods of study to suit your learning style. As you are probably already aware, there multiple different learning styles, including visual, auditory and kinesthetic. Never underestimate the power of studying to suit the way that your brain is wired! Traditionally, teachers love making their students copy notes of the board and create detailed summary books ect, however, this is not effective for everyone. While this may work for visual learners, this style of learning is just not suited to the auditory or kinesthetic learner. Here are a few study suggestions for each learning style:
Visual: If you are a visual learner, chances are that making colour coded summary notes will work for you. Remember to take the time to repeatedly reread through them before your SAC or exam. In addition, you could also watch graphical videos (i.e. not just close up shots of people taking), print info of the internet and read through and highlight key points, or read your textbook. I myself am a visual learner and have found that anything that involves reading, writing or graphical content (e.g. useful pictures) is the most effective.
Auditory: Auditory learners study best by listening. Methods include; recording yourself reading through a textbook or study notes, then listening to the playback over and over, watching videos that involve talking, or getting a friend to quiz you on your knowledge. Listening to music whilst you study can also aid concentration.
Kinesthetic: Kinesthetic learners learn best by doing. Suggestions include; creating detailed posters or flow charts, making models and diagrams or doing practical experiments (may not be feasible for every subject), and teaching others the content (audience can be real or imaginary!). Also, studies have shown that fidgeting with an object whilst sitting in class can help kinesthetic learners to absorb and retain information.
If you are not sure what learning style suits you best you can take this quick quiz:
https://www.how-to-study.com/learning-style-assessment/Hope this helps you to study more efficiently!