Common mistakes students make while preparing for or taking the GMAT include neglecting a structured study plan, focusing too much on one section while ignoring others, underestimating the importance of timed practice, and relying solely on shortcuts without understanding underlying concepts. Test-day errors, such as poor time management, rushing through questions, and overthinking or second-guessing answers, also negatively impact scores. These mistakes can be avoided by creating a balanced, consistent study schedule, regularly taking full-length timed practice tests, analyzing mistakes to strengthen weak areas, mastering core concepts, and practicing effective time management strategies. Maintaining focus, confidence, and a disciplined approach ensures more accurate performance and maximizes score potential.