Hello Abu Kalam

for scoring above 80 marks in JEE you should follow some basic steps

1. Go through all the formulas of 11th and 12 PCM

2. Then You have to see the weightage topics that mostly comes in JEE  question paper.

3.  For JEE Chemistry subject you just prefer NCERT ,for Physics you Solve some questions from Arihant or Universal self scorer and for maths you can prefer Arihant

4.You have to solve various levels of previous year paper and Mock test.

5. The day Before exam you just try to solve 5 question paper which will give you an idea about the difficulty level.

6. While giving test you should be 100 % sure while marking an answer bcz a wrong answer can minus your mark.

I hope you liked my ans

Thank You and GOOD LUCK for JEE !!!!