(g) Material from prerequisite courses. With regard to material from previous courses, I don't really take any time before the start of a course to review the prerequisite material, but do actively refer to notes/textbooks on those topics throughout the term, especially in the beginning, to help with the current course. Based on my experience there are usually only a few things from a previous course that are heavily used, and by going back to the notes on those topics in the beginning of the term, I usually find it to be quite manageable. Sometimes the same concepts are taught in a different perspective, and I think it's important to build that connection between the different interpretations.

(d) Review notes: before each midterm and final exam, I always read the slides and textbook, and make a set of review notes. This includes key concepts, important derivations, and simple examples. I find myself understanding the material much better after writing the important things down neatly. I put more emphasis on things that I am confused about and refer to this set of notes through my exam prep period.
(e) Questions: while I make my review notes, I write down any questions that I come up with beside the corresponding section of the notes. After the notes are completed, I come back to these questions and see if I can answer them having gone through all of the materials covered.
(f) Exam and homework problems: I always keep all of my returned midterms and homework sets. I think it’s important to look back at the problems I have done after a while. For the questions I got wrong, I analyze what caused the mistakes and make sure I understand the concept so that I can avoid making the same mistakes again. For the questions I got right, they can serve as a good refresher to the concepts that might not have been touched on for a while.

(a) Pre-reading: I try to go through the pre-readings for the next class a day in advance. I don’t necessarily aim to understand everything, but rather get familiar with the material. I find the lectures to be much easier to follow this way.
(b) Formulas: I always derive the formulas and equations introduced in the class at least once, in a way that I am most comfortable with, which might take a different form than the ones introduced in class. This for the most part saves me from memorizing them and ensures understanding of the material.
(c) Note taking in class: I don’t think it’s enough to just listen in a lecture, no matter how focused I am. A lot of the times, it is not the things on the slides, but rather the professor’s explanations to what’s on the slides that help me understand the material. I write these things down in class, as quite often, these things are not documented in any of the materials provided for the class.

Advice from AmStat News, in an interview with Greg Campbell, biostatistician in the US Federal Government.
Most biostatistical jobs require at least a Master's degree on statistics or biostatistics, so one is well-advised to take lots of courses. I personally adhere to the philosophy that good applied statisticians need a solid mathematical underpinning. This will enable one to be undaunted in picking up a journal article with formulas in it or to innovate if the problem does not quite fit the textbook example. So, my other advice is to take a variety of coursework in order to expand your toolbox. And, of course, education need not end at the university; it can be a lifelong passion.

Confucius saying: I hear and I forget; I see and I remember; I do and I understand. That is, there is a big difference between memorization and understanding. To achieve understanding, you have to DO enough textbook examples/exercises and homework problems to grasp the steps of logical reasoning.

Please see the next few items for quotes from various sources.