The most critical stage for improving the chances of clearing the UPSC exam is the preliminary exam. Success in this stage is essential in determining eligibility for the subsequent mains and interview stages. To maximize chances of selection, aspirants need to focus on thorough preparation of the syllabus, consistent practice through mock tests, and effective time management during the exam. Additionally, understanding the pattern and nature of questions, developing quick decision-making skills, and strengthening their general knowledge base are crucial for success in the preliminary exam.