I follow a fairly strict routine before any big exam, and I'm actually using it at the moment because I'm preparing for my nursing licence exam here in Manila.
It starts the night before. I stop studying at around eight, because I've learned that last-minute cramming just makes me panic. I lay out everything I need on my desk: my ID, two pens, a pencil, a water bottle and the admission slip, and I check it twice. Then I eat something light, usually rice and fish that my mother makes, and I go to bed early. In the morning I get up at least two hours before I need to leave. I do ten minutes of stretching, have a proper breakfast, and on the way to the test centre I listen to the same playlist of slow songs. Just before I go in, I do a breathing exercise where I breathe in for four counts and out for six, three or four times.
I started all this in my final year of secondary school, after a disastrous maths exam where I forgot my calculator and was so flustered I couldn't think straight. My aunt Maricel, who's a teacher, sat me down and helped me build a routine. The reason it works, I think, is that it takes away decisions. On a stressful day, I don't have to think about what to do, because I've done it all before. It also gives me a feeling of control. The playlist, especially, tells my brain that this is a familiar situation, not a threat, and by the time I sit down at the desk I'm usually focused rather than frightened.