Candidates can improve their writing skills for UPSC by practicing structured answer writing regularly. Techniques such as outlining answers before writing can aid in organizing thoughts and maintaining clarity. Additionally, focusing on proper grammar, vocabulary, and syntax will enhance professionalism. Reading high-quality answers from previous candidates or model answers can also serve as a benchmark. Incorporating relevant examples and data in answers showcases depth of knowledge, and timed writing sessions can help improve speed and coherence in actual exam conditions.