Ask or find out how the tests are scored. If they are based upon the number of right answers, then go through the test answering all the ones you know for sure. Then go back to the beginning and begin answering the rest. DO double check as you go to make sure you are answering the right question in the right area (I have NO idea what the tests look like ok?)
Breathe. Don't over think. Make sure you read the question for just what it wants in the way of an answer.
Do you have a noted accommodation need, and are they aware of it if so?
See if this helps it talks about different computer exams:
Strategies for taking a Computerized Test