Act as an experienced SEO content strategist with 5+ years of expertise in optimizing website performance. Provide a detailed guide on best practices for writing SEO-friendly URLs, ensuring they are both user-friendly and search-engine optimized. Include the following key elements: [1] Proper use of keywords (e.g., placement, density), [2] URL structure (e.g., hyphens vs. underscores, length), and [3] Avoiding common pitfalls (e.g., dynamic parameters, uppercase letters). Also, address how [WEBSITE TYPE] (e.g., e-commerce, blog) and [TARGET AUDIENCE] (e.g., tech-savvy users, general public) influence URL strategy. Finally, provide [3 EXAMPLES] of before-and-after URL transformations to illustrate your points.