Candidates can prepare for interdisciplinary questions in the UPSC exam by maintaining a broad knowledge base that integrates information from various subjects. They should focus on establishing connections between disciplines like politics, economics, and environment, enhancing their analytical skills. Regularly practicing with past papers and current affairs helps candidates identify overlapping themes and patterns. It is also beneficial to engage in group studies to discuss and debate cross-disciplinary topics, thus developing a holistic understanding. Utilizing resources from diverse fields supports the candidate's ability to answer interdisciplinary questions adeptly.