Very little of what follows will change what you know. All of it can change how much of what you know you get to use.
A week out
Confirm the test centre address and how long it takes to get there at the time you will be travelling, not at some other time of day. If it is somewhere you have never been, go and look at it. This sounds excessive and removes an entire category of morning-of stress.
Check exactly what identification you need and that the name on it matches your registration. Mismatches are not negotiable at the door.
If you take medication, wear glasses, or need anything accommodated, resolve it now. Accommodation requests are not same-day processes.
The day before
Logistics and rest. Pack what you are bringing, set two alarms, and eat normally.
Do not sit a full practice exam. Do not start a new topic. If you cannot tolerate doing nothing, a light pass over your own notes is fine, but be honest that it is anxiety management rather than preparation, and cap it.
Sleep is the single highest-yield thing available to you on that day, and it is the one most often sacrificed to studying that will not move the result.
The morning
Eat something you have eaten before. This is not the day to discover how a new breakfast agrees with you.
Bring food you can eat quickly and that does not require a fork, plus water. Bring layers, test centres run cold or hot and you do not get to choose.
Arrive early enough that traffic is irrelevant.
During the exam
Decide your break strategy in advance. You have a finite pool of break time across the day. Divide it before you start: short breaks after the early blocks to stand and drink something, a longer one in the middle to eat. Left to the moment, most people either skip breaks and fade badly in the last blocks, or take one long break and then feel rushed.
Set a per-block pacing checkpoint. Know roughly where you should be at the halfway point of a block, and check once. Checking constantly costs time and composure; never checking means discovering the problem too late.
Let bad questions go. A question you cannot resolve is worth exactly as much as any other question. Flag it, answer something, move on. Carrying it into the next three questions is how one loss becomes four.
Expect blocks that feel terrible. Practice exams and the real thing both contain stretches that feel like you are failing. The feeling is not well correlated with the result, and the students who leave at lunch convinced it has gone badly are frequently wrong.
Afterwards
Do not reconstruct questions and look them up. It is not actionable, it is reliably distressing, and the recall is worse than you think.
The week before, in more detail
Wind the intensity down rather than stopping abruptly. A hard taper from full days to nothing tends to produce restlessness rather than recovery; a gradual reduction across the final week leaves you rested and still in rhythm.
Shift your sleep schedule to match exam morning if it does not already. Doing that in the final two nights does not work, the body needs longer, so start it a week out.
Do a light, timed block at the time of day your exam starts, once or twice. Not to learn anything, but so that sitting down to hard questions at that hour is familiar rather than novel.
What to do if something goes wrong on the day
Traffic, a documentation query at the desk, equipment problems. These happen, and the useful thing is to have decided in advance that they are survivable.
Arriving flustered costs you the first block if you let it carry. The recovery is mechanical: sit down, breathe, accept that the first few questions will feel worse than they are, and let the rhythm return. It generally does by the second block.
The students who lose a day to a bad start are usually not the ones with the worst start. They are the ones who spent the next two hours thinking about it.
If you change one thing
Decide your break strategy before the morning. It is the one decision you will otherwise make badly, under fatigue, at the point where it affects every block that follows.
Frequently asked questions
Should I study the day before?
Light review at most. The marginal knowledge gained is small and the cost to sleep and composure is not. Most people who study hard the day before do it to manage anxiety rather than to learn.
How should I use the break time?
Decide in advance. A common approach is short breaks after early blocks and a longer one around the middle for food. Improvising means you will either skip breaks and fade, or overrun and feel rushed.