For tackling the optional paper in UPSC Mains, aspirants should select a subject they are genuinely interested in and have a strong background in. A deep understanding of the core topics is essential, so regular reading and thorough revision of the syllabus is necessary. Practicing answer writing and focusing on previous years' question papers helps familiarize candidates with the exam pattern. Engaging with reference books and scholarly articles enriches knowledge. Additionally, seeking guidance from mentors or joining dedicated coaching for the optional subject can significantly enhance preparation efficiency.