Psychological preparation for the UPSC interview should include developing self-confidence and effective communication skills. Candidates should engage in mock interviews to practice articulating their thoughts clearly under pressure. Understanding common interview questions, such as those related to personal background and current affairs, allows for better preparation. Additionally, candidates should be aware of their body language, as it plays a significant role in conveying confidence. Stress management techniques, like deep breathing or visualization, can help candidates stay calm and composed during the actual interview.