Dear Lasya,

Assuming you are to appear for the JEE Mains 2020, I am answering your question. As you have enough time left, I think this will be the right time to start preparing. 

• First and foremost, make sure that you are thorugh with your NCERT books, escpecially Physics and Chemistry. Read and understand each line and don't forget to make notes.
• After finishing each chapter, complete all the problems given at the end of each chapter. Next start solving NCERT Exemplar problems.
• After you are through with all these steps, start solving problems from a suggested reference book.
• Keep track of your speed and accuracy while solving your problems.
• Take regular mini tests after completing each chapter. Mock online tests are available for free in the internet.
• Don't get a feeling of comfort as you are in the OBC category. Competition gets tougher each year regardless of caste. So keep preparing and give your best.
• Maintain an error notebook and fill it after each test.
• Take full mock tests and practice previous year question papers ater you complete the syllabus and revision. More than all, be determined and do smart-work. All the Best!