To prepare for the Public Administration paper in the UPSC Mains, candidates should start with key texts like Public Administration by Mohit Bhattacharya and review NCERT books. Understand fundamental concepts such as Administrative Theories, Public Policy, and Governance. Incorporating current issues and case studies will enrich responses. Regularly practicing answer writing and analyzing previous years' papers will help refine one’s approach and improve time management during the examination. Additionally, interactions with successful candidates or mentors can offer invaluable insights.