Twenty-four hours before an exam is too late to be talking about what you know and what you don't know. If you haven't kept up over the semester, your best chance now is to ensure you know what's in the exam and be confident in the areas you did cover. That means, today is not the day to be adding new material to compensate for the last few months of not staying on track. It will only be confusing and you may forget both what you do know as well as the new material.
Focus solely on the exam(s) of the following day. The day before an exam is not the day to start learning French, a new Coursera course or even preparing for a different subject's exam in a few days.
If you have been preparing but are still nervous, don't fill your head or thoughts with random things. Consider exercise, a brisk walk outside or meditation in place of social media updates or streamed content.
Studies over the years have shown that reading or learning before bed increases retention, so before falling asleep the night before, run through all your exam notes once or twice or maximum benefit.
Calm your stomach and your mind
Eat food you know is safe and doesn't upset your stomach. Watch out for oily, fried, dairy, spicy and any foods or restaurants that have been suspect in the past. If you have an especially sensitive stomach, it might be best to avoid these foods for at least two days before an exam. Nerves will do enough to your stomach on their own.
Eat low glycemic index (GI) foods, such as beans, lentils, some pastas, grainy breads, oats, quinoa and some fruits such as strawberries, apple, apricot or peach. The real benefit here, for non-diabetics, is you'll be able to stave off mid-exam hunger and cravings.
Eat more protein. Protein, even more so than low GI foods, keeps you satisfied longer and provides around the same energy in calories per 100 grams as carbohydrates with a lower risk of feeling bloated.
When choosing carbohydrates, choose complex carbs such as wholegrains, brown rice, beans, quinoa, sweet potato, green peas, apples, bananas, berries or carrots. Again, you'll be less likely to have trouble during the exam, unless you're sensitive to high fiber food.
Avoid sugary foods, alcohol and performance-enhancing drugs as they can have adverse effects on your body and mind which can wreak havoc on your ability to focus, recall and analyze during an exam.
Skip caffeine the day before. Depending on how sensitive you are to caffeine or if you drink it too late in the day, you could lose necessary sleep and hinder focus and alertness on exam day. It may also add to any anxiety you may have.
Caffeine on the day of the exam, if you must, should be consumed immediately before the exam. This will decrease the chance that a caffeine drop will occur during the exam.
Clothes and bag prep
Select comfortable, loose clothing and lay them out ready to throw on in the morning. Do this early in the day in case you need to do laundry. The fashion police will be too concerned with their own exam rather than what other people are wearing, so go with whatever makes you feel good, such as sportswear, sweatpants or even the oversized touristy shirt an aunt gave you last summer. If it really bothers you, bring a change of clothes.
Bring a bottle of water. Still water is best to avoid any unwanted "side effects" in a quiet exam room that could interrupt your flow.
Pack a pencil case with at least two blue pens, black pens, sharpened pencils, mechanical pencils, plus a correction/whiteout pen and an eraser.
Only bring summarized exam review notes you need for last minute cramming.
Turn on autopilot
Know where the exam is and by when you need to be there. Write down the address, where it is exactly (building, floor, room), exam begin and end times (in case someone asks on the day when they should pick you up) all on a Post-It or smallish piece of paper to reduce carry load.
Have a plan for the morning in 30-minute increments. From getting up, brushing teeth, eating breakfast (and what you'll eat), when you'll get dressed to when you need to leave. If you use public transport or drive, know the route, timetable and approximate arrival time, ideally giving yourself at least 15 minutes inside the exam room to set up and run through last minute reviews.
On the day
Get up early. Set multiple alarms not more than five minutes apart to prevent falling into a deep sleep if you hit snooze. Ask someone to wake you up by coming to your room or calling you. Don't rely on texts!
Don't freak out or let others influence your mood. Even better, don't talk to anyone taking the same exam during the entire 24-hour period.
Most will advise against last minute review, but if you have been cramming or have something you know you'll need and memory isn't one of your strong points, look at that material as close to the exam as possible and as soon as writing commences, jot it down on your exam paper somewhere as a reference for when you need it. This helps when it concerns complicated formulas, case names, grammar rules, specific numbers, names or titles.
Schedule a small reward for after the exam. The reward or celebration is something to look forward to and will get your mind off how you think you performed. Consider retail therapy, a movie or your favorite meal.
Breathe deeply and know it'll soon be over. There are others just like you right now and each of you will survive.
Whatever you think you achieved can't be verified for some time and can be dealt with later.