Do the easier questions first! These generally tend to be towards the start of the paper.
2 marks for an easy question is worth the SAME as 2 marks for a hard question.
You want to sweep up as many marks as you can within the first half hour.
Flag any difficult questions and come back to them at the end.
Keep an eye on the clock and be conscious of your progress throughout the exam.
Check that you have answered every question. Do not miss any pages.
Keep in mind the list of silly mistakes that you made in your preparation. Do not repeat them in the exam - double check your answers.
Make sure you include units if applicable (e.g. cm, seconds, degrees).
Answer the question in the format that is asked of you (e.g. SIMPLEST FORM, EXACT VALUE [which normally means surd form], INDEX FORM, SIGNIFICANT FIGURES, SCIENTIFIC NOTATION, DECIMAL PLACES, NEAREST WHOLE NUMBER, DEGREES AND MINUTES...).
If a question has multiple parts (e.g. a, b, c, ...) that are related, generally the solutions to the earlier parts will help you to solve the later parts.