Your question is too broad. You should have access to past exam papers from your institution, ask your tutor(s).
If you can post a specific question of the type you are struggling with, we can help you through it.
Generally, the best approach is practice, practice, practice. Memorisation will only get you so far. We have sticky topics at the top of this forum for online and textbook resources - but it is best to work through past exam questions from your institution as these will be at the difficulty level you can expect on your exam. Also check reading lists you have been given for your course as many textbooks have practice questions.