Essential preparatory materials for success in UPSC exams include comprehensive textbooks, NCERTs, and reference books covering the syllabus. Aspirants should also utilize current affairs magazines and trusted online platforms for up-to-date information. Regularly taking mock tests and previous years' question papers helps familiarize candidates with exam patterns and identify weak areas. Joining coaching institutes or study groups can provide valuable guidance and resources. Finally, aspirants must prepare notes and summaries to reinforce learning and aid revision before the exam.