NCERT textbooks are undoubtedly the best for preparation of Jee mains. Many questions are directly asked from NCERT Textbooks. So you first complete these books for a clear concept and basic preparation. But to score a good percentile, you must follow some reference books like HC Verma for Physics, OP Tandon for Chemistry and R D Sharma for Mathematics. These books are recommended by top educators. Do limited books but do it more times. Along with this, you must solve previous year exams and sample papers as these papers will help you to have a clear view of what types of questions are asked. Solving previous year exam papers are highly recommended as many questions from past years are repeated sometimes.