Unless your usual way of working is on a computer, in your exams you are going to have to write. Not only that, you will need to write quickly.
This is a very useful skill to develop, especially if you plan to continue to college and beyond.
How can you do this? How can you go from taking an hour to write a page of A4 to 15 minutes?
Get sample questions from the teacher. Time yourself. Write.
Find other opportunities to write: keep a diary, write letters, write a short story. Just write. The more you do it, the quicker you will get.
Don't worry about being neat, but keep it legible. The examiner needs to be able to read your ideas, otherwise it's all a waste of time.
Always plan. It is amazing how many times I will tell a class about the genius of planning and they simply ignore this and go straight into writing, then they wonder why their writing is too wordy, or they've picked the wrong question and run out of ideas.
Planning organises the points, ensures you have definitely picked the best question and clears up any mental clutter so you start writing entirely focused on the question.
Ultimately, any long answer in English revolves around making key points, whether it is a writing or a reading task. The points become the outline structure and then you pad with either your quotations and analysis (Reading/Literature) or your reasons and supporting evidence (Writing). Planning these key points and selecting your quotes OR planning your points and creating your supporting evidence is five minutes at the start of the exam that could save you a huge amount of misery when you dry up part way through or start repeating yourself and wasting time.
3. Check your grip and posture
Many people experience pain when writing. This not uncommon. I know I get tense when marking and it can hurt my hand, arm and shoulder.
Try different pens until you get one that feels comfortable when you hold it and don't grip it too hard. You can even buy pen grips that can help you to hold a pen comfortably. This is really worth exploring if you get writing pain as you need to enable yourself to write as easily as possible in your exams.
Don't press too hard and try not to tense up. Again, practise helps.
Have breaks: stretch and wiggles your fingers and rotate your hand both ways.
Always write with the pens you will use for your exams. Get used to how they feel in your hand and how they write. Make sure you have plenty of them. Make sure they are black ink.
Resist the urge to write in pencil. You will have to write in black pen in your exam, so get used to it.