To select relevant case laws for the Law optional in UPSC, aspirants should focus on landmark judgments and principles that have established precedents. Utilizing legal journals, commentaries, and UPSC syllabi will help in identifying significant cases. Keeping track of recent judgments from the Supreme Court and High Courts is essential, as these influence current legal principles. Joining discussion forums or study groups can also aid in discerning which cases may be most beneficial for preparation. Regular revision and frequent application through mock tests can further clarify which case laws are essential for the exam.