To be effective as a PR writer you'll need to learn the basics of journalistic style. Unless you're a regular newspaper reader, a lot of this won't come "naturally." And you will have to unlearn some things you've been taught about writing.
You've already taken the first step, with your analysis of some journalistic elements in the news item you analyzed. You determined who was at the center of the story, what they were doing that was newsworthy, when and where it took place, and why (or how) -- in what way -- it was significant enough for an editor to take notice. Those are the "5 W's" of journalism. Editors expect a story to be clear on the 5 W's.
If your client likes the story but the editor doesn't, you go nowhere. When you've gotten a sign-off on your press release, from your boss and/or your client, it's sent to an editor -- sports editor, food editor, business editor, etc., depending on how you addressed it.