To improve retention of historical facts for the UPSC exams, several strategies can be effective. Creating chronological timelines helps visualize events and their sequences, aiding memory. Engaging with primary sources and historical narratives can make learning more absorbing. Additionally, summarizing information in one's own words reinforces understanding. Regularly revisiting and discussing historical themes in group study can facilitate deeper insights. Lastly, connecting historical events with contemporary issues and current affairs can strengthen the relevance and retention of these facts.