Always include the term you are focused on in your slug. Start doing this routinely before publishing any of your blogs. The target keyword is the primary phrase you want to rank for. You might use tools like Yoast SEO to see if the desired term appears in your slug.
In a URL structure, stop words are unnecessary phrases or words. If you eliminate those words, your slug would still have significance. For instance, prepositions, articles, and numerals.
Make sure the words are always in lowercase while updating your slug. The way it eventually reads and looks is due to a technical cause. Lowercase URLs are considered differently by web servers like Apache than uppercase URLs.