Develop a mark per minute ratio (e.g. 1.5 hour exam - 90 marks = 1 mark per minute) and occasionally check the clock to see that you are on track with time. However don't check the time too frequently and don't check if it causes you to panic.
Write out any formulas/acronyms before you start.
Use a system to quickly categorize questions into those you know well, those you know something about, and those you know little about.
Start with the questions you know well.
General Exam Writing Tips
Read directions carefully.
Read questions carefully (re-read if necessary).
Be clear on what the question is asking and make sure you are answering the actual question before you begin answering. Don't read more into the question than is there.
Underline key terms and information.
Start with some easy questions.
Write legibly.
Spend time according to mark allocation − don't spend too much time on low mark questions.
Work at a reasonable pace, even if you don't complete the exam.
Use all the exam time allotted (it's not a contest to see who can leave the exam room first).
Check over your exam.
Ignore what others are doing (especially early leavers).
Don't compare yourself to others.
Don't discuss the exam with others (before or after the exam).
Before You Hand in Your Exam
Review your answers.
Check your calculations and units.
Change answers only if you are sure of the change.
Ensure your name is on all pages.
Check that you've answered all questions.
Check that your answers line up on the answer sheet.