Common pitfalls of UPSC exam preparation include inadequate time management, laziness in revising important topics, and reliance on too many study materials. Many candidates also underestimate the importance of answer writing practice, neglecting to develop concise and impactful answers within the stipulated time. Additionally, failing to stay updated with current affairs can severely impact performance. It's crucial to maintain consistency and quality in preparation, focusing on revising key concepts and regularly practicing mock exams to avoid these pitfalls.