Practice-exams.
It’s the most effective and quickest way.
50% studying & 50% applying your knowledge
For every half hour of studying, you take the same time to take practice tests.
Why? Easy - each test question targets very specific abilities. Are you going to have to write an essay, short answers, do a multiple choice test or solve math problems? Are you going to have to argue, analyze, reproduce knowledge or explain? By taking practice exams you get used to how you’re supposed to apply what you remember. How you use what you remember is often more important than how much you really remember.
It’s also a lot more active than studying. You have to reproduce your knowledge and apply it. You don’t just read about Entropy or the Categorical Imperative, but actually have to answer questions about it and explain it, which is a lot harder. You will get a better sense of what you actually do understand and what you should maybe look at a little closer. It’s super easy to seemingly understand a concept when you have your notes, that you just read, right under your nose. Explaining requires a true understanding of the matter at hand.
Personally I always try to find previous exams of that teacher about the same subject and if I can’t get any, I’ll phrase questions myself. Try to narrow down what the test is actually about as much as possible and take into account on what concept the teacher lay great stress on.
After doing a practice exam you correct it yourself, using your notes and phrasing more ideal answers. You will become quite aware of what you already know and what topics you should focus on. Plus you’ll be less nervous when taking the actual test!