Common pitfalls candidates should avoid while preparing for the UPSC examination include lack of a disciplined study schedule, failing to manage time effectively, and neglecting mock tests. Candidates often mistakenly underestimate the vastness of the syllabus, leading to inadequate coverage of important topics. Additionally, focusing too much on one subject while neglecting others can create imbalances in preparation. Poor handling of stress and anxiety can also hinder performance, making it important to maintain a healthy study-life balance. Establishing a structured approach towards preparation enhances chances of success and minimizes the likelihood of these common pitfalls.