Hello,

I would rather suggest you to join any online test series program of good coaching institute.It will help you in practice and self assessment of where you stand.You should solve also the previous years questions at the same time.Focus on applying concepts and formulas to the questions.

You can easily score good marks if you can solve previous years questions and mock test but at the same time to attempt these, your concepts needs to be clear from ncert books.

Good luck.

IIT JEE is one of the toughest technical exams that require a lot of hard work and a better strategy to crack the exam.They should know the syllabus as well as the paper pattern so that it would be easy for them to prepare. 

https://www.digialm.com//OnlineAssessment/index.html?223@@M131

https://jeemain.nic.in/webinfo/QuestionPapers2017.htm

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