This is so subjective. I am interested in the comments to come. My methods are not efficient at all, but very effective.
For example, let's say that there are 5 chapters. I study chapter 1, hard. Move on and study chapter 2, hard. Go back and re-study chapter 1, then chapter 2, and then move on to study chapter 3, hard. Repeat this process of going back to re-study the previous chapters in a sequential order (first to last) to the point where you already know what information is on what slides/pages. Then get a good night sleep. Wake up very early before exam (4-5 am) and read through chapter 1-5 again; at this point it should be easy to recall.
This method utilizes both long-term and short-term memory. Hardly efficient, but does the trick.