The majority of us will have to go though an examination period in our lives, be it in primary, secondary, or higher education. Wheter we like or not, it's relatively impossible to avoid having to sit exams, barring exceptional circumstances. Learning to cope with both the revision process and exam period for myself has definitely been a work in progress throughout my academic life. Despite finished four years of university, I would still say that each year I am continuing to learn better methods of dealing with them, especially as someone who deals relatively badly with the stress and anxiety of exam pressure and academia in general.
Revision Tips
Do not overreach in the goals you set to complete each day!
This is something I fall short with every time, and especially have this year. every day I would wake up and say 'today I am going to finish this topic, then start this topic, then complete that topic.' Every night I would go to bed not having completed what i set for myself, and feeling like I had failed as a result. Realistically, i had just massively over estimated the amount I could physically get through in twenty four hours!. Setting yourself ridiculous expectation is your own biggest downfall, it will make anything you do not seem good enogh and you will never feel like you're achieving anything.
Set yourself realistic goals!
I personally do not use revision timetables: each year I spend hours drawing one up, allocating time for each day, only to completely ignore it when i actually begin. If they work for you then great, by all means maximise their use if they aid your time management. Instead I set myself rough goals of what I should have completed by either the end of the day of the end of the week, and work as hard as I can to meet those goals. It is so important to remember that we are only human, our brains can only deal with, process, and remember a certain amount of information in a period of time, and rushing to cram it all in only detriment you learning process. Go slowly and be kind to yourself.
Keep stocked up on food and drink
If I said that i only ate some veg, buscuits and fruit during revision I would be lying. I practically lived off crisps, chocolate, coffee, and sometimes junkfood. But to an extent, as long as you feel well physically and mentally, I strongly believe that during a period as stressful and potentially sad as exams, eat whatever you want that will make you happy, be that healthy or maybe not so healty food. Obviously there are huge benefits of healthy eating, but I personally need comfort food when I am working 12+ hour days. Water however, is so immensely important, as is energy providing food like brown pasta. Drinking water frequently throughout the day and stocking up on slow releasing energy food really does make a difference: I really notice a difference when I have forgotten to keep drinking water. Keep a big bottle on your desk near you and it will be harder for you to get distracted.
This one might be a personal/nerd preference, but I love stocking up on new pens, good quality paper, and revision cards so much. It makes such a difference for me, be it psychological or not. Start as you mean to go on and invest in the tools you need to make your revision notes vibrant and clear ro read because it really does make a difference having your notes visually clear and bright.
Making your notes clear, condensed, and colourfull 
How you actually physically lay out your revision is very much dependent on your subjects. My degree is in food technology and agriculture, it's not equally as essay based always, but I personally work very visually, and benefit the most from hand writing notes, especially for my final project exam. I start off be condensing notes on a topic into a word document which I highlight on word, and print out. From there I condense them into handwritten notes (diagrams, bullet points etc), and then again into 5-6 revision cards for each topic. For me, highlighters and coloured pens are key. I will have microbiology notes in blue, key points in red, facts in green, for example. This is obviously dependent on the individual, but for me it ingrains it in my mind much more. I can be sat in an exam and think 'what was highlighted pink and written in green half way down than revision card?' and it can help jolt a memory. Find out what works for you.
Exam Tips
The night before my exam for final project, I had two hours sleep and then threw up the next morning. I did well in the exam but felt like I was dying in the process, and it could have been detrimental to my performance as a result. Sleep is so incredibly important, although the recommended eight hours might not be achievable, at least try and get six-seven the night before an exam. It truly does affect how alert you are, and if you have an afternoon exam you will slump before you even go in.
Put yourself in a calm situation pre-exam
There is nothing have more than being around people before an exam, especially people sitting at the same one. Listening to someone discuss things you have never heard of throws you off track so much and completely messes up your focus. I am lucky to have my comfort zone next to my class, so pre-exam I walked around that a couple of times before I hearded into the exam. 
Exceptional circumstances
This is very much dependent on your institution/university, but if you have been suffering with a long term health issue that has taken up time in terms of doctors appointments, illnesses etc, you have the option to apply for exceprional circumstances, meaning said issue will be taken into account with your exam result.
Lastly, but most importanly, remember that exams, regardless of the level you are sitting them at, are not the be all and end of life, no matter how much pressure you are under or how much you have riding on said exam. From experience, both personally and from countless friends over the years, messing up, not getting what you wanted, and even completely failing an exam can be rectified. Retaking can be an option, and there is always the chance to change the course you had set out, and whilst this may not be appealing or what you had planned, alternatives do exist. One day you will look back and realise that whatever happened, everything turned out alright in the end.
People our age are under immense pressure in our education systems, and trylu do not think we get enough credit. So remember to give yourself a pat on the back, and just do the best you can, because at the end of the day that really is all you can do. Good Luck!