So many responses to this that I'm not sure this hasn't already been posted:

3 weeks or more before a test - it's all about understanding high-level principles. Focus on really trying to understand the material. Could you explain it to a friend or have you just skimmed it to tick some kind of studying goal you set yourself?

Less than 3 weeks before a test - it's all about past papers, specifics, and short-term memory. Do a past paper as well as you can in the allotted time. Then see what you can do if you let yourself go past the time with an open book. Then step away from the paper for an hour or so and come back and mark it. The next day work on whatever you scored worst on in the paper to the extent that you really understand what you were being asked to do.

Make acronyms as necessary. I find batches of 3 acronyms work best when learning them initially, and then revisit daily as you build up a bank of them. You'll be surprised at how many you can remember - 50 or so is definitely do-able and is easily enough to get you through any set of exams you might ever take.

Rinse and repeat.

You'll find that passing most exams right up to high-level professional qualifications (I have a PhD and am an actuary) becomes pretty straightforward with this formula