Two simple piece of advice I can give you are:
1)Make sure you have a FUNCTIONAL WATCH and all required exam equipment, and mentally calculate how long you have to spend on each question, and stick to that time limit, do not spend too long on any single question.
2)Make sure you have replicated exam condition before the exam and practiced under such conditions as well as getting someone-i.e. your teacher or tutor to mark your responses for you. Getting used to working under timed pressure will increase your chance of improving your performance under exam pressure.
One extra tip is to really focus on recognising that exams are not meant to trick students, they are designed primarily to test student's knowledge, so they will always test what you have already learnt, so just always consider how does the content you have learnt applied to the exam and just do your best. At the end of the day, remember you won't be the only one with these exam nerves, with practice, you will learn to manage it well and perform your best in exams. Hope this helps and all my best wishes for you to ace your studies this year