In the first ten minutes of the first paper you will feel your heart rate spike. Your hands may shake. This is a normal stress response and it will pass. Your job is to have a plan for what to do while it passes.
Do not open the paper immediately. Take three deep breaths — four seconds in, six seconds out — before you turn to page one. That buys you thirty seconds and calms your system.
Start with a question you know you can do. Not necessarily question one. Skim the paper for a friendly one and start there. Confidence unlocks the rest.
If you get stuck on a question, put a small dot next to it and move on. Come back after you have finished the rest. Sitting stuck loses points on questions you could otherwise get.
If a wave of panic hits mid-paper, put your pen down for ten seconds, breathe, and re-read the last sentence you wrote. Do not close your eyes for long. Ten seconds and you are back.