Hi, I'm a writer, and I'm also an expert inthis particular area. And I have something that I'd like to do a story query. "
If you are querying an editor with a story/article idea, you have to grab his attention right away. "I'm a writer, etc" will not do that. Plus, obviously he'll presume you're a writer, why else would you be contacting him? It's unnecessary information. You must explain to him in a very few paragraphs what your story is about, why it is unique and will be interesting to readers, and what your qualifications are regarding the topic.