This will ensure that you are prepared for the type of exam you will be sitting, whether multiple choice, short answer or essay.
Know what you are expected to do: for example, how many questions from each section will you have to answer. Of course, you still have to read the instructions on the paper itself and make sure that they are the same, but this will help you to feel comfortable with what will be expected.
Even more important, make sure that you have practiced the right type of questions, and know what will be expected of a ‘good’ and ‘bad’ answer.