JEE Main exam is said to be one of the toughest exams as it tests your conceptual knowledge. Since around 6 months are remaining now , it's advised to start with the preparation. Some tips - 

● Choose 2 books per subject which are the best ones as it will save your time

● Make a proper time table and follow it strictly 

● Solve previous year papers

● Write down all the formulaes and key concepts 

● Do writing practice as well. 

Hope this helps.