Few thoughts on practical things you could consider...
Focus on question practice. Any gaps in your knowledge will start to gradually embed if you keep repeating questions. Pick a topic area that's shaky, attempt one question as far as you can without referring to anything. Review against the answer and mark yourself harshly. Go back, repeat the question referring to notes when you get stuck and using them to help you complete it. Mark the answer. Repeat repeat repeat until you don't need to check your notes anymore. Move onto a new topic area. Repeat the same approach, then go back to the first one and do some more questions to keep it fresh.
Do not look at model answers before attempting questions. You'll sit there thinking "yeh, I knew that" when actually would you have written it? Probably not.
If your technique is at issue, tackle questions in terms of addressing that rather than content for a while.
So, timing, practise calculating exactly how many minutes you're going to spend per question part based on marks. Practise monitoring yourself. Practise forcing yourself to stop and move on. Practise leaving lots of white space (write on every other line). Make sure you answer every single question. If you write nothing you get no marks.
Practise dissecting questions without trying to answer them. Pull the question apart, label it up, annotate everything that comes to mind, jot down what you think it wants, pay attention to the different types of phrasing used to request different styles of answer. Practise reading slowly and not making assumptions about the question you think it's asking rather than what it's actually asking. Then compare your dissection to the marking scheme / model answer.
For case study, practise looking at the scenario in isolation and thinking up every possible idea, question, piece of advice, problem, etc etc that may be relevant or useful. Then after you've done that compare to what you're being asked - what did you miss that would be relevant to the question?
Remember not to over explain. Don't focus on minor extraneous points, or detailed explanations that are not helping your score. Bag the basics and move on. If you're being asked to write for a particular audience, put yourself in their shoes and think like them.
Keep breathing. Keeping a calm, cool head makes a huge difference to your ability to properly understand a question and formulate a coherent answer. Tell yourself "I can do this". If you feel yourself start to panic force yourself to slow down or stop, focus on your breathing and slowing it down, then resume.
Don't sit re reading and re writing your notes or texts. Practise questions, especially the questions you struggle with and master it that way. The only way to improve things like exam technique and timing are through practising and being prepared to change your usual approach if it isn't working for these exams.
Question question question question. But set yourself regular breaks to get up and have a drink or mental break.