When I did GCSE geography, I made flashcards on each smaller section, e.g. each type of plate boundary or feature of a river. I also made a flashcard or poster for each case study (just memorise a few facts about each one). You could also do practice questions from a textbook or ask your teacher for a practice paper. If it's related to your topic, you might also find it helpful to watch a documentary or a Youtube video.
I would appreciate if you let your friends know too.