According to the National Library of Medicine, around 25-40% of all U.S. students suffer from some form of test anxiety. Experiencing some nerves before a big test is normal, but serious test anxiety can affect you physically and even impair your performance. However, there are some strategies you can use to cope:

Prepare well and start early: Knowing that you’ve done everything you possibly could have before going into a test will reduce your anxiety and boost your confidence. Starting to study early as possible is another useful strategy, as it’s one that has been proven to improve your performance, and there are few things more stressful than last-minute cramming.
Visualize success: Visualization is a technique often used by athletes before a big game of competition, but it can work for test-takers, too. Imagining how the testing day will go step-by-step and that it will go well will train your brain for what to expect and help to reduce anxiety.
Use relaxation techniques: Relaxation techniques such as meditation, yoga, or deep breathing help to re-center you and expand your awareness of your own body. Pick a few techniques to use regularly and help ground you whenever you feel overwhelmed.
Stay healthy: It’s easy to let habits such as eating well and getting enough sleep fall by the wayside when there’s a big test coming up, but these habits matter more than ever when you’re in the midst of studying. Practicing good time management can help you to stay on top of everything and perform at your highest level.
Get ready for test day beforehand: Prepping the night before, such as laying your clothes out, planning your breakfast, or packing your bag, will allow you to arrive early, unharried, and ready to do your best.
Don’t be discouraged: Even if the test doesn’t go as planned, failure is normal and a natural part of the learning process, and there are nearly always opportunities to make up lost ground. Try to keep everything in perspective, even though that may be difficult at the time.

And finally,

Seek help if you need to: If these thoughts and emotions ever become overwhelming or feel out of your control, there is absolutely no shame in seeking out counseling or therapy, and you are far from alone in doing so. Speak to a trusted adult or guidance counselor if necessary.