Just clear your head and relax. Time yourself, allowing the same amount of time that is given for a regular quiz or test. If you are accustomed to completing the exam in a certain amount of time, you will have time left to go over and catch little mistakes that usually are overlooked. Review old quizzes and tests. If you have access to material from previous semesters, use that as a guide.
Professors usually follow the same pattern when designing tests.
If your tests during the semester were all multiple choice, expect multiple choices on the final. Pay close attention to how the questions are worded. Be able to pick out key words that will let you know what the professor is asking. Go with what works for you. If your method is different from what I have suggested here, and it works for you, stick with it.