There are two diffrent sides of preparing for the comprehension: firstly, you need to work on your literacy and vocabulary - that means how well and how widely you can read, understand and use words. This will help you answer the comprehension questions really well, because it increases your understanding. Secondly, you need to practice spelling, punctuation and grammar, so that you can be really well understood when writing your answers, and in your creative writing. The best way to improve all these skills is reading! It's also the msot enjoyable way, which is good news. Read what you like, push yourself if you feel up to it, and your vocabulary and literacy will definitely improve. There are also websites and books that can be reccommended which will provide spelling, grammar and punctuation tests which you can complete little and often to really make sure you know your stuff.