Aspirants can best utilize flashcards for UPSC exam revision by creating concise notes that encapsulate key concepts, definitions, and important dates. These cards can aid in quick recall and reinforce memory through spaced repetition. Utilizing color coding or imagery can enhance engagement and retention. Regular review sessions using flashcards help identify weak areas needing further revision. Group study sessions also allow for collaborative learning, as students can quiz each other with their cards. Furthermore, digital flashcard applications offer flexibility, enabling aspirants to study on-the-go, making revision more efficient and effective.