It can be achieved only through a mixture of hard work and smart work. Your JEE Main score also gives a fair indication as to how much you would be able to score in JEE Advanced.
Concepts should be crystal clear in your mind.
Learn basic and important concepts thoroughly.
NCERT books are your best bet to crack JEE Mains.
However, to score above 300 you need to have that extra edge!
DC Pandey and HC Verma are the best books to build concepts in Physics.
SK Goyal would be ideal for Maths (Algebra).
Maths is a scoring subject and if you are referring to this book, you can easily score around 80% here.
1. Absorption of concepts (conceptual learning)
2. Application of concepts (problem-solving)
3. Analysis of performance