Successful strategies used by previous toppers in the UPSC exam include a well-structured study plan, prioritization of core subjects, and consistent revision. Toppers often emphasize the importance of understanding concepts rather than rote learning and utilize a variety of resources, such as standard textbooks and online materials. Regularly taking mock tests and solving previous year papers helps in gaining confidence and honing exam techniques. Many toppers also advocate maintaining a balance between academics and personal well-being to prevent burnout. Lastly, cultivating a positive mindset and resilience in the face of setbacks are key attributes that distinguish these successful candidates.