Online exams are something new to the education industry and students. Before taking an exam online, familiarize yourself with the exam program/site you will be using. Read the directions thoroughly and acquaint yourself with the process before the test so you are comfortable and confident with the site when it's time to take the exam.
In most cases, you will be asked to log onto a secure site with a username and password. Your exam will likely be timed as a further measure to ensure you are the one taking the test. Review your answers carefully, and pay attention to commands, as some online tests will not allow you to hit the “back” button on your browser or minimize/maximize the screen. Be absolutely certain you are finished with your exam before you finsh and submit. If you make an error on your test or have technical difficulties, alert both the IT helpdesk and your professor.