I found the best way to prepare for them when I was doing them was doing them in class. Usually once a class one of us would give a monologue to the teacher while the other 2 did other work...meaning that we were able to practise and get feedback on a weekly basis so that by the time came around we knew what we were doing in the exam
when i prepare for them, i focus on the structure rather than focusing solely on vocab or whatever - if you have a basic knowledge of the areas uve studied, you can say basically anything in the same sort of routine/structure and so this might make you feel more comfortable when you are doing it. so anyway i dont know if will help you but heres how i go about them
so first of all - answer the question or state your opinion of it
then there are two typed of structures i usually follow:
1: if my opinion is very one sided regarding the question
- introduce one point with a topic sentence
- define any terms that relate to the question and a background knowledge to the argument you are putting forward (keep it brief tho)
- then i say a specific example, so if the question was about peer pressure, i might say that loads of teenagers get affected by peer pressure at parties and behave differently, drink too much etc.
2: if the question is kind of two sided
- topic sentence for one side
- define any terms that are particular to your argument, maybe ask a retorical question to engage the examiner
-give a specific example
- then repeat this for any negative/opposite argument you have
i say my conclusions the same way basically every time. i repeat the question/answer it/give my opinion on it - then i justify my opinion once more by listing or briefly outlining the things i have talked about already...
hope this helps.. im terrified about doing mine still