Hello Rohan,

In order to score a good marks in the JEE Main & JEE Advanced examination, the following tips could be very helpful for you-

The main thing is that you have to build your concentration level, then only you can stay focused on your goal. I would like to say that please limit the study time between 10 to 12 hours and please increase your concentration and speed of reading, understanding and solving the problems then you will not face any kind of difficulty.
For preparation of exam, the most important thing is your confidence after that you should know the whole syllabus and make your plan properly for learning new chapters, solving the numericals and revision. All three things should be the part of your preparation strategy in daily routine.
Your basics in Physics, Chemistry & Mathematics should be very clear upto 12th std. You should read the NCERT books for basics. Then HC Verma for Physics, RD Sharma for Mathematics, OP Tendon for Physical & Inorganic Chemistry, and Organic Chemistry of "Arihant Publication" for detail or extra knowledge. 
You should also try to solve the previous years question papers, this helps too much and you should also give the mock test to rectify yourself and build your confidence level.
For more preparation tips, importants topics & books, you can go through the link given below
Https://engineering.careers360.com/articles/jee-main-2019
In this way, you can prepare well for the JEE Main and the JEE Advanced.
Thanks for query on this platform, you may visit again
All the best for your examination.

Hello Rohan,

The best books for jee mains are:

1. For physics;

• HC Verma Concept of Physics Part 1.
• HC Verma Concept of Physics Part 2.
• IIT JEE Physics by D.C. Pandey.
• Problems in General Physics by I.E. Irodov.
• Physics for IIT JEE by Resnick, Halliday, Walker.
• Problems in Physics by S.S. Krotov.

2. For chemistry;

• Organic Chemistry by Morrison Boyd.
• Organic Chemistry by O.P. Tandon.
• Inorganic Chemistry by O.P. Tandon.
• Modern approach to chemical calculations by R.C. Mukherjee.
• Numerical Chemistry by P.Bahadur.
• Concise Inorganic Chemistry by J.D. Lee.

3. For Mathematics;

• IIT Mathematics by M.L. Khanna.
• Differential Calculus by A Das Gupta.
• Class XI and XII Mathematics by R.D. Sharma.
• Trigonometry, Geometry Books by S.L. Loney.
• Problems in Calculus of One Variable by I.A. Maron.
• Higher Algebra by Hall and Knight.

The best books for jee advances:

1. For Mathematics;

• R.D. Sharma by Maths XI & XII 
• Hall Knight by Higher Algebra
•  I.A. Maron by Problems in Calculus of One Variable
• Arihant Prakashan by Algebra
• Arihant Prakashan by Differential Calculus
• Arihant Prakashan by Integral Calculus

2. For physics;

• H.C. Verma by Concepts of Physics Vol I and II 
•  I.E. Irodov by Problems in General Physics 
• Halliday, Resnick & Walke by Fundamentals of Physics 
•  S S Krotov by Aptitude Test Problems in Physics 
•  Nelkon and Parker by Advance Physics 
•  S.L. Loney by Dynamics of a Particle & of Rigid Bodies

3. For chemistry;

• O.P. Tandon by Physical Chemistry 
•  P. Bahadur by Numerical Chemistry 
•  Bruce H. Mahan by University Chemistry 
• R.C. Mukharjee by Numerical Chemistry
•  P. Bahadur (For Reading Theory) by Physical Chemistry
•  P.W. Atkins by Physical Chemistry

Hope this will help you. Best of luck.