In order to achieve good marks in any class, all you need to do is just doing a thorough study. Make your concept very clear and practice difficult questions frequently. You should also prepare notes of your own with little “to the point” definitions and solutions, so that it can help you when you revise the topics for your examination. Do not go for too many books but try to select few good books and read from them. Never forget to read your own NCERT book. That’s all. Good Luck..