While preparing for JEE Advanced, one of the biggest mistakes students make is focusing too much on memorizing formulas instead of developing deep conceptual understanding, which is essential for solving its application-based and multi-concept questions. Another common mistake is ignoring revision and mock test analysis, as many students keep solving new problems but fail to learn from their errors, which slows down real improvement. Some also rely on too many books and resources, which creates confusion rather than clarity, while others delay difficult topics instead of tackling them early. Poor time management and lack of consistency can also seriously affect preparation quality. The best approach is to build strong fundamentals, practice selected high-quality problems repeatedly, revise regularly, and analyze mistakes carefully to continuously improve performance.