Hello Sauradip,

For IIT-JEE preparation you can focus on some main points such as - 

Know what you want. Learn Time management skills. Create a study schedule for yourself. Know your strengths and work on weaker areas. Make class notes. Stay positive in critical situations. Be with people who motivate you. Ask for help when in doubt.

Divide your work into chunks never do it as a whole and go out , take a walk , enjoy nature once in a while to clear your mind. Practice mindfullness.

Feel free to ask if you have any more queries. All the best!!