Recently I sat my WSET level 2 and did pretty well. I scored 90% in the exam, which is a pass with distinction. Based on that experience, these are my tips for anyone else planning to take the course.
Before it begins, you will be sent copies of the textbook, workbook and a lexicon of terms to use during tastings. The workbook suggests you'll need to do at least 28 hours of home study in addition to the classroom sessions and you should definitely be prepared for that aspect. None of the subject matter is difficult to learn in and of itself, but there is a lot of it and your best weapon is to be well prepared.
If you can make the time, try to read the entire textbook cover-to-cover before you attend the first session. The subject matter can be quite dry in parts, so you'll probably want to spread this out over a number of days. There are 20 chapters in total and covering 3 or 4 chapters a day can be achieved quite easily, so setting aside a week for this is a fair estimate.
Even better than reading the textbook, though, is to know as much as possible organically before you begin. This advice may seem unhelpful but during my course, some of the other students mentioned in passing that they'd never tasted a Riesling. When you're trying to memorise facts about more than 30 different grapes, the regions they're grown in and all of the different wines that are made from them, it really helps to have a visceral knowledge of as many as possible. Remembering the difference between Rieslings from Rheingau and Mosel, for instance, is much easier to do when you can recall the taste of Rieslings from personal experience. Spending time trying unfamiliar wines before you start the course will really pay off and hey, who doesn't enjoy drinking more wine?
The workbook is provided for you to take notes during the sessions but actually I didn't find it that helpful having done the preparation. I preferred to focus all my attention on listening to our instructor, lest I miss some of the detail in what was said. Your mileage may vary of course, but if you've already done the prep you should be able to treat the actual sessions more like a top-up to your base learning.
It's important not to dismiss any of the less prominent sections, such as grape-growing, food-pairing or social responsibility. There will be questions on them and they won't always have obvious answers. If you treat those topics as seriously as you do the chapters on actual wines and spirits, it will earn you extra points come exam time.
Regardless of how much you study, though, nothing is going to prepare you for some of the more ambiguous questions that you'll encounter in the exam. You shouldn't worry too much about this because most of them are very straightforward, but there will definitely be a few curve balls thrown in too. If you want to get as close to 100% as possible, you should be ready for these. The best approach is to try and discount the obviously wrong answers first. Then make sure you weigh up every single word in the question against the remaining answers. There will be a clue somewhere, perhaps in the presence of just a single word like "aged" or the name of a region.
Lastly, make sure you use the textbook as your canonical source of truth. Some of the topics are simplified, which is reflected in the exam questions. If you're also learning from other sources, they may have a more detailed, nuanced take, which can seem to contradict the black-and-white nature of a multiple choice exam.