You've probably heard this a million times but its all about practicing. Realistically, if you think about it, in the exams there are going to be questions that will test your knowledge. In order to answer these correctly, you will need to have the required knowledge.
To gain the knowledge, do questions in your own time. Can be from anywhere, majority of students will prefer past paper exam questions from physics and maths tutor. Or you could use text book questions. Get to a point where you're answering every question correct, and you will be fine.