Hello Mahimesh. You should refer to your class 12 ncert text book and the study material provided by your respective coaching institute where you are studying. But the main preparation part actually lies on you and not on the book you are using. So I would recommend you to not read too many reference books and start preparing from the materials that you have. Try to find books with previous years question papers and their solutions. That way you can analyse the important topics asked in exams and you can study accordingly. You can also give online test series to analyse where you stand in the preparation of the exam. NTA also conducts a mock test series so check their official website too.

You can refer to the below link for some tips to appear in jee mains 2019.

https://engineering.careers360.com/articles/jee-main-preparation-tips

Hope this helps. For any other questions please feel free to comment down below.

Good luck!