1.First of all , have faith in you and tell yourself that you can study and score good marks.
2.Read your lessons regularly and that will result in reading your question paper and answering it fast. By reading them regularly they get inside your brain without you struggling and you can find grammer mistakes easily.
3.Never learn the exersices by heart or reading. Write them and learn until you can determine the answer yourself as soon as you get the question.
PS - If you are in KV, then the most questions in your question paper will be from the exercises.
Hope this helped you. Best of luck!!!