The best thing you can do is to get to know the main ideas of both set pieces and predict the questions you might get asked. Ask yourself: why did the IB choose these pieces? What do they want me to say about these pieces? Your teacher will most likely provide these answers for you. Take all the concepts, everything your teacher has provided, anything (credible) you have found online, and write practice essays on each possible point. When you get to the exam, you will probably have done at least one of the questions during your revision. This applies to any IB subject.
Also, you need to get as familiar as possible with your set pieces. This might seem obvious, but if it is done well, you can ace this section of the exam. I suggest listening to them LOADS and get so familiar with the score, that in the exam you can remember exactly where/when things occur, without hearing the music physically. Some people can hear the music in their head instantly without having heard the piece before, which is pretty cool. However, some people can’t and that is completely okay. Just listen to the pieces; learn to love, or at least appreciate them. The examiners will be able to see this in your answer, which is a plus.
I would happily help you get comfortable with these pieces and will aim to answer all of your questions. This section of the exam is the one you can prepare for the most, so let’s make sure you get those marks!