How to score good marks in less time? What would be your strategy?

My exam possibly going to start in the next month. I have not prepared well. I need advise that how can I prepare for my exam fast and what should be my strategy. I am a student in high school, and in our school i-ready is a common tool which is used. There are total 14 chapters that I have to learn but as of now, I have read only 4 chapters.

Thank you, Looking for some helpful answers.