Common mistakes candidates make while preparing for UPSC exams include poor time management and inadequate understanding of the syllabus. Many aspirants fall into the trap of following a rigid study schedule without flexibility, leading to burnout. Additionally, reliance on a single source of information can limit perspectives, and neglecting current affairs can result in a lack of crucial knowledge. Lastly, some candidates often underestimate the value of answer writing practice, which is vital for scoring well in the examination. Recognizing and addressing these mistakes can significantly enhance preparation effectiveness.