Best practices for writing essays in UPSC exams include several important guidelines. First, ensure a clear understanding of the topic to effectively address the prompt. Structure your essay with a compelling introduction, coherent body paragraphs, and a strong conclusion. Use relevant examples, case studies, and statistics to support your arguments, enhancing your credibility. Maintain clarity and coherence throughout the essay by using proper transitions between ideas. Writing regularly to develop your style and seeking feedback can improve content and presentation. Lastly, managing time effectively during the exam is crucial to ensure all parts are addressed adequately.