Student

If it were me, I would commit to one chapter a day. In each chapter, I would write down key points from each. After the 20 chapters are done, I would spend the next 5-7 days going through my notes and making up different ways to remember things. Then spend the remaining time going back through the book to see if anything may have been missed that was important.

Skim each chapter before reading it. This gives your mind a chance to become familiar with the content and build background knowledge before taking notes.
Try assimilation of content. In other words, relate what you're reading to what you already know as you're reading it.
Try to find patterns in the content while you're reading, or put similar information together. This will help alleviate working memory capacity.

Whatever your study environment is, make it as closely related to the environment you will take your exam in.
If you are one who needs to listen to music to study, make sure it is music you already know and keep it as low as possible. While taking your exam, recalling these songs will be helpful for remembering what you read when you heard them.

Hopefully this helps. Good luck!