If you come across a question that is too hard, or one on which you draw a complete blank, place a mark beside it and move on. Come back to it later. You may find the answer somewhere else in the test. Answer every question at face value. Do not try to guess what the instructor wants.
First intuition is often correct.
If you do guess, do not change an answer without a good reason. Read on and see. As you read each multiple-choice question, cover the choices with your hand and try to answer the question in your mind. Then check to see if your answer is listed as one of the choices. As in life itself, few, things are absolute.