Here are a few options for a WordPress `post_tag` description, each with a slightly different focus:

**Option 1: General & Concise**

* **Title:** 信件撰寫
* **Description:** 學習如何撰寫有效率、清晰且專業的信件。涵蓋各種不同類型的信件，如商業信函、求職信、感謝信等等。 (Learn how to write efficient, clear, and professional letters. Covers various types of letters, such as business letters, cover letters, thank-you letters, etc.)

**Option 2: Focused on Practicality and Skills**

* **Title:** 信件撰寫
* **Description:** 掌握信件撰寫的技巧，包括格式、語氣、和內容組織。提升你的溝通能力，在商業、個人和專業環境中表達清晰。 (Master the skills of letter writing, including format, tone, and content organization. Improve your communication skills to express yourself clearly in business, personal, and professional environments.)

**Option 3: Highlighting Different Letter Types**

* **Title:** 信件撰寫
* **Description:** 探索不同類型的信件撰寫指南，包括：商業信函、求職信、邀約信、抱怨信等。學習正確的格式和有效的表達方式。 (Explore guidelines for writing different types of letters, including: business letters, cover letters, invitation letters, complaint letters, etc. Learn the correct format and effective methods of expression.)

**Option 4: Emphasis on Correctness and Clarity**

* **Title:** 信件撰寫
* **Description:** 專注於準確性和清晰度的信件寫作。學習如何避免常見錯誤，確保你的信件易於理解，並有效傳達你的信息。 (Focus on accurate and clear letter writing. Learn how to avoid common errors and ensure your letters are easy to understand and effectively communicate your message.)

**Key Considerations when Choosing:**

* **The target audience:** Who are you writing this blog for? Are they beginners or more experienced?
* **The content of the blog posts:** What specific aspects of letter writing will you be covering?
* **SEO:** Consider including relevant keywords that people might search for (e.g., “商業信函”, “求職信”, ” letter writing tips”).

You can choose the description that best suits your specific needs and the overall theme of your blog. Remember to adapt it to your blog’s voice and style! I recommend testing out a few different ones over time to see which ones generate the best results.