Characteristics of a well-structured answer in UPSC exams include clarity, coherence, and relevance. A strong introduction sets the context, followed by a logical flow of ideas divided into paragraphs. Each paragraph should present one clear argument or point, supported by examples or data where applicable. Furthermore, maintaining an appropriate length and sticking to the question's requirements is crucial. Conclusively, a summary that reiterates key findings can enhance the overall impression. This organized approach ensures answers are impactful and demonstrate a candidate's depth of understanding of the topic.