I have worked with dozens of students who were writing administrative law for at least the second time. I found that the number one pitfall students fall for is relying on their notes blindly without understanding the material.
What I mean by that is that students would essentially copy their notes into the exam paper and expect to pass so long as they mention the "right" cases. This is known as the "boilerplate" answer.
Copying your materials or simply discussing cases which are relevant to the issue on your exam is not sufficient for you to pass your exams. Many students also rely on answer templates. There is no substitute for understanding the material on this exam.
Having a good set of CONDENSED notes is a necessity, especially for admin law. But even more important is understanding those notes and how each topic relates to the other. If you are going through your notes and you see Knight, Baker, and a number of other cases yet you cannot explain how each case relates to the other than you haven't fully grasped the material in the syllabus. You need to relate all the concepts in your head so that you can apply your knowledge on the exam.