When you take an exam in English there are two things you need to practice. The first thing you need to practice is your knowledge of English. You need to practice your grammar, reading, writing, listening, speaking, and vocabulary.
I love writing. I think writing is fun and relaxing! But, getting your ideas into words that sound good written down can sometimes be tricky. Even very strong English speakers have trouble writing at the same level.
Listening can be one of the most difficult skills. There are so many accents, and how people speak in real life can be very different to the listenings you do in the classroom. One of the problems is finding videos with good subtitles.