Successful UPSC aspirants recommend various resources for self-study, including NCERT books for foundational knowledge and standard texts like Laxmikant for Indian Polity and Goh Cheng Leong for Geography. Online platforms like Coaching apps, YouTube channels, and dedicated websites provide valuable insights and mock tests. Aspirants also suggest using previous years' question papers and reference books tailored to the syllabus. Group studies and discussions further enhance understanding and retention of complex topics, fostering a well-rounded approach to the UPSC exam preparation.