If you have enough time start then go through standard books and start studying,if about 2 months left just revise what you know,and if less than a month is remaining do as much of previous year as possible,if only a night is left just go through last 2-3 years papers think positive feel like winner,remind ur achievements and give ur best shot.
In my view, we need to keep focus on the basics perfectly and then revise the previous papers of last years so that you can get the confidence that you can clear the exam.