Stop studying an hour before the test. Seeing something you don't know at the last minute could make you more anxious. Spend the last hour relaxing, doing something unrelated to the exam. Do not talk about the test with other students, once you get there. If need be, sit in a corner by yourself.
Anxiety can be very contagious.
Others may say something you forgot to study, and then you may forget what you did study. Take a few deep relaxing breath. During stressful situations breathing becomes shallow and rapid. Practice taking the test. Go to the room where it will be held and familiarize yourself with the surroundings.