Years of theoretical and applied work has demonstrated that it is the quality of the revision that you do not the quantity so try to establish some simple rules that experience and empirical research have shown to work. Having said that it should be obvious that it is never too late nor too early to start revision. Revision is not a memorising task per se it is much more to do with constructing information in such a way so that it becomes readily accessible. These are strategies that you can learn readily and then apply not only to the individual chapters but also the overall ideas. Although mastering these strategies will not make the critical reading process an easy one, it can make reading much more satisfying and productive and thus help you handle difficult material well and with confidence.
Most readers annotate in layers, adding further annotations on second and third readings.
Annotations can be light or heavy, depending on the reader's purpose and the difficulty of the material. One difficulty with this, of course, is that when you re-read it is sometimes difficult to separate out the stuff that you have already highlighted from the other material. Learning about a text before really reading it. Previewing enables readers to get a sense of what the text is about and how it is organized before reading it closely. This simple strategy includes seeing what you can learn from the headnotes or other introductory material, skimming to get an overview of the content and organization, and identifying the rhetorical situation.