Best practices for writing answers in the UPSC Mains Examination include clarity, structure, and relevance. Candidates should start with a concise introduction, followed by well-organized body content and a strong conclusion. Employing bullet points or subheadings enhances readability. Using relevant examples and data while avoiding unnecessary jargon can effectively convey the answer. Time management is crucial, ensuring all questions are attempted. Lastly, writing legibly and reviewing answers minimizes errors, contributing to a better overall score.