I did this recently and discovered that many of the contributors to these sites don't know the correct answers. Research the answers for yourself. You really want to know the material and not just answers. Make up some flash cards to help you remember key concepts or lists. Take a sample test from Microsoft or Transcender.
Free samples are available or full versions can be purchased.
Pick a test date and shoot for it. Block out the time you need to be ready. Don't wait too long, as there is a lot of information you will need to retain. Don't plan to take two tests on the same day. Lastly be prepared to regroup if you fail.