Firstly, study the entire paper and have a look at every question given in the paper. Decide which section to start from and which question to try first. Aim at the questions you are comfortable with first and then reject the final questions. Stop wasting your time on questions you don't understand the answer to. After completing the entire paper, check how long it will take to complete it. Start by checking the questions and list the mistakes you made and write them down on separate sheets. Review the mistakes made and practice the idea repeatedly. As a result, the same mistake never happens again.