Common pitfalls candidates encounter during UPSC preparation include poor time management, lack of a clear strategy, and overwhelming stress. Many aspirants fail to understand the vast syllabus, leading to ineffective study routines. Another common mistake is neglecting revision and focusing too much on new material, which hampers retention. Additionally, candidates may get caught up in distractions like excessive social media usage or unproductive study sessions. It's crucial to maintain a structured approach, regularly analyze progress, and adapt strategies to avoid falling into these traps.