A medical exam is not going to be in the same format as the TOEFL. Some tests may be in a multiple-choice format while others have a speaking or listening section. For this reason, you should have a good understanding of the format of the test you are going to take.
By using the process of elimination on multiple-choice questions, you will greatly increase your chances of choosing the correct answer. Simply eliminate the answers that you are certain are wrong and choose from what is left.
You should answer every question, even if you need to guess. Since there is no penalty for wrong answers, every question that you skip is a missed opportunity for gaining points.
You should not rush through any question, regardless of how easy you think it may be. The test is designed to challenge you, so take the time you need to think through each question and then maintain that pace throughout the test.
Mental fatigue can play a significant role in the success or failure of one of these tests. Take short periodic breaks to allow your mind to rest and regroup.