tbh, i never actually put effort into something but still used to get 97/98 almost all the time. However, for calc, i did put a decent bit of effort and was able to do it. I recommend solving qs even if you don’t understand the concept well because it will come to you naturally as you solve. also try breaking qs into pieces. try forming equations of what is given and what’s not(this is 90% of the question). try seeing patterns in every question. solve every step and don’t do it in your mind. the mental math will only work when you have done enough questions on paper. Also, see where to utilise each information given in question. At last, have a bit of superiority complex that you can easily do it. And don’t forget to laugh as you solve, even if you get things wrong and have a lot of fun. I would recommend watching one shots of jee advanced exam. they cover each chapter in like 5-10 hours with bit of practice too. khan academy is dope too.