When selecting study materials for the UPSC, candidates should consider reliability, relevance, and comprehensiveness. Materials must be aligned with the UPSC syllabus and cover all important topics thoroughly. Candidates should prioritize resources by respected authors or institutions. Additionally, considering peer recommendations and reviews can help in identifying effective resources. Balancing standard textbooks with current affairs sources and reliable online platforms is also crucial for a well-rounded preparation. Regularly updating study materials helps candidates stay abreast of changes in the examination pattern and syllabus.