Design of applications URLs has been taken center stage in recent years since they act as one of the key factor in improving usability and search-engine rankings of your application. Thus, special attention is required while devising the URL scheme for your application beforehand rather than allowing the URLs to just be generated during course of development/evolution.

“Make Your URLs Clean and Human-Friendly”

Yes, that should be the thumb rule while devising the URL scheme. URLs should be short, easy to type, help user visualize the site structure.

Based of the same thumb rule there are some DOs & DONT’s that must be taken care of:

• Design URLs not to assist implementation rather for describing content: Prefer URL like “/articles/case-study-summary” rather than “/website/articles/cachedversion?ID=103&title=case-study-summary”. The second version can be easy and straightforward & assist developer in providing the desired behavior in application but actually is neither good to memorize nor SEO optmized.
• Prefer Content title/description over IDs: Even if IDs are important to provide the desired behavior & cannot be neglected since they uniquely identify the required document, you can use the URL like “/articles/103/case-study-summary”
• Make URL scheme hierarchical: Create a sense of hierarchy (for example, /Products/Menswear/Accessories/Sunglasses), so your
  visitor can guess the parent category’s URL. This would assist user in easy navigation and enhance usability.
  
• Avoid spaces, code or special characters: If you want a word separator, use a hyphen (as in /articles/case-study-summary). Underscores or other special characters are unfriendly, and URL-encoded spaces are bizarre (/articles/case+study+summary) or disgusting (/articles/case%20study%20summary)
  
• Persistent URLs:Do not change URLs. Broken links (404) equal lost business. Make sure all URLs live forever and continue to point to relevant pages. In case you need to change URLs, you must try to support the old URL schema for as long as possible via permanent (301) redirection.
• Avoid Typo errors in URLs: Typos unknowingly increases 404 errors (broken links) since despite quite guessing the URL right, users would not end up getting the correct page. Use a spelling-checking web server to minimize the damage caused by the inevitable typos.

Apart from this, there are some minor recommendations:

• Be case-insensitive & don’t use mixed case URL since it makes hard for users to memorize. Usability would increase if web servers would ignore case in resolving URLs
• Be consistent. Adopt one URL format across your entire application.
• Do not use file name extensions for HTML pages. Web browsers do not care about file name extensions if you set the MIME type appropriately.
• Shorter URLs are better since users often type them manually.

So, focus on your url building strategy before pitching into website implementation.