Before you take a test (or exam, or quiz, or assessment; whatever your teacher may call it), be sure you

know what kind of questions you will be asked (essay, multiple choice, true/false, fill-in-the-blank, matching, etc.)
study ahead of time
review material ahead of time
know what you are being tested on (which material, topics, lectures, videos, discussions, etc.)
know if the test covers just the current material, or all the material in the course up through now
know if the test is timed or not (if timed, how much time?)
know how many chances you get to take the test
know what are you allowed to use during the tests (calculator, book, notes, special materials, nothing, etc.)
know when will you get your test results
know if you take tests online or if will you need a proctor
schedule time to take your test

And get yourself ready, personally