Mathematics

Congratulations on scoring 81% in your first attempt at JEE Mains! Here are some tips that can help you prepare for the second attempt:
Analyze your previous attempt: Start by analyzing your previous attempt and identify your weak areas. Work on improving those areas first before moving on to the other topics.
Create a study plan: Make a study plan that covers all the topics in the syllabus and allocate time for each topic based on its weightage and your proficiency in it. This will help you stay organized and focused. Solve practice papers and mock tests: Solve as many practice papers and mock tests as possible. This will help you get familiar with the exam pattern and improve your speed and accuracy.
Revise regularly: Make sure to revise the topics that you have already covered regularly. This will help you retain the information and improve your performance.
Focus on time management: Time management is crucial in JEE Mains. Make sure to practice solving questions within the given time limit. This will help you improve your speed and avoid panic during the exam. Stay positive and confident: Stay positive and confident throughout your preparation. Surround yourself with positive energy and motivate yourself to achieve your goals.
Seek guidance: If you are facing difficulties in any topic, seek guidance from your teachers, seniors, or coaching institutes. This will help you clear your doubts and strengthen your concepts. Remember that consistency and dedication are the key to success in JEE Mains. With proper planning and hard work, you can improve your score in the second attempt. All the best!

A list of the Best Books For JEE Mains and JEE Advanced is mentioned below;
Physics:
1- NCERT Textbooks.
2- IIT Physics by D. C. Pandey
3- Problems in Physics by S. Krotov
4- Problems in General Physics by I. E. Irodov.
5- Fundamentals of Physics by Halliday, Resnick & Walker.
6- Concepts of Physics Vol I and II by H. C. Verma (Highly Recommended)
Chemistry:
1- NCERT Textbooks
2- Organic Chemistry O. P. Tandon. Organic Chemistry Peter Sykes.
3- Physical Chemistry O. P. Tandon. Organic Chemistry MS Chauhan.
4- Concise Inorganic Chemistry J. D. Lee. Organic Chemistry Morrison and Boyd.
5- Modern Approach to Chemical Calculations R. C. Mukherjee. Mathematics:
1- Maths XI & XII by R. D. Sharma.
2- Differential Calculus by A. Das Gupta.
3- Algebra Higher Algebra by Hall and Knight.
4- Calculus: Problems in Calculus of One Variable by I. A. Maron.
5- Co-ordinate Geometry: Plane Co-ordinate Geometry by S. L. Loney.
6- Trigonometry & Geometry: Plane Trigonometry Part 1 by S. L. Loney.
7- Course in Mathematics for IIT-JEE by Tata McGraw-Hill publications.
8- Objective Mathematics for JEE Main & Advanced and Other Engineering Entrance Examinations by R. D. Sharma. For more information, you may visit the Shiksha JEE Main exam page. (https://www.shiksha.com/engineering/jee-main-exam). I hope this will help you.