When choosing study materials for the UPSC interview, aspirants should consider relevance, credibility, and diversity of sources. Materials should align closely with the interview focus, which includes current affairs, general knowledge, and personal interests. It's essential to opt for resources authored by experienced mentors or reputable institutions to ensure quality and accuracy. Moreover, incorporating varied formats such as books, articles, and videos can provide a well-rounded perspective. Finally, aspirants should evaluate materials that encourage critical thinking and allow them to engage with complex topics pertinent to the civil service framework.