Candidates prepare for the UPSC interview, or Personality Test, by engaging in extensive self-reflection and mock interviews. Understanding their own background, achievements, and aspirations is crucial. Aspirants should stay updated on current affairs and have a strong grasp of their optional subjects. Practicing answers to common interview questions and receiving feedback from peers or mentors can build confidence. Participation in group discussions may help improve their ability to think on their feet and communicate effectively during the actual interview.