hi,

see I assume you are asking about jee advance exam which is the entrance test for admission in btech courses of iits, see it does not matter which school or college you belongs to, you need to self study and practice a lot, makes your conception of mathematics physics and chemistry cristal clear. so after completing the 10th exam you need to study the basic syllabus of 10+2 course then you have to solve the questions paper, mcqs books by tata macgraw.

also you may take special coaching or tuition in the relevant institution.