Hello Anupama,

For preparation of exam, the most important thing is your confidence after that we talk about syllabus. You should know the whole syllabus of jee main exam. Your basics in Physics, Chemistry & Mathematics should be very clear upto 12th std. You should read the NCERT books for basics only. Then HC Verma for Physics, RD Sharma for Mathematics, OP Tendon for Physical & Inorganic Chemistry, and Organic Chemistry of "Arihant Publication" for detail or extra knowledge. 

You should also try to solve the previous years question papers, this helps too much and you should also give the mock test to rectify yourself and build your confidence level.

Thank You