Approaches to tackle difficult subjects in the UPSC syllabus include breaking down complex concepts into manageable parts, utilizing visual aids like mind maps, and creating summaries. Group study can also facilitate understanding, as peers can provide different perspectives on challenging topics. Regular revision and practice exams help solidify the learning process, while resources like online courses or tutoring can offer additional support. Setting specific goals and rewarding progress in difficult areas can enhance motivation and engagement with the subject matter.