A good slug identifies the page without reproducing every word of the headline. Keep the main topic and distinguishing detail, then use Slug Generator to normalize spacing and punctuation.
Review the result for accidental meaning changes, ambiguous transliteration, and collisions with existing slugs. Avoid dates unless the page is date-specific. If the page is already public, consider redirecting the old URL before changing its slug.
What title and current URL are you working with?