Candidates preparing for core General Studies (GS) papers in the UPSC mains should focus on understanding the syllabus thoroughly. This involves mastering key concepts and themes through standard textbooks and current affairs sources. Time management is crucial; candidates should allocate ample time for each subject and practice writing answers within set time limits. Regular revision to reinforce learning, along with thorough analysis of past papers, can enhance answer quality. Moreover, candidates should integrate interlinking concepts across subjects to develop a comprehensive approach to tackling questions effectively.