Reading is a must and very important but periodically write down what you have learned in your own words. This is really very helpful when you are preparing for the exams. Try to derive equations (Physics, Chemistry) solve mathematical problems or anything you feel you are challenging. This way you will prepare indirectly for your exams. Imagine you are solving an equation for the first time in the examination hall. Any error will stop you at that point itself and you grow nervous if you are not able to solve it. You will lose time and you will not have adequate time to complete the question paper. So take it seriously. Write down periodically whatever you have studied. Solve equations or problems several times till you are confident that you can do easily. Take several mock tests before the exams. You can get previous year question papers over the internet or they are available with the book sellers. I once again reiterate that writing is a very good practice to score good marks in the exams.