You know the pattern of each subject. And the marks from each chapter is also fixed. If you don't know about the marks from each chapter, find out from your teacher or internet.
Give more importance to the chapters which have more weightage. Find important questions from each chapter- all kinds of question like short, medium and long. read the answers from a sample paper or anything and write them. Don't forget to write the answers on your own after studying.
For mathematics, you need to practice more and more. The best way is- have a separate copy and solve at least 10 random questions from the chapters you have already studied daily.
Remember that there is no shortcut for success!!!