Having a good idea and expressing it well isn't enough. In order to be a successful—that is, published—op-ed writer, you need to know how to pitch. The essence of a good pitch is deceptively simple: You need to tell your editor (or future editor) enough about an idea to be interested, but not enough to overwhelm, bore, distract, or otherwise discourage him/her from responding to your query.
For the Op-Ed page, a pitch is usually short—like op-eds themselves—and you will have better odds of success if you send the finished op-ed along with your pitch. (For magazine features, on the other hand, you may pitch an idea you haven't yet reported or written a single word about.) Pitching is most often done by email, not by fax or snail mail. You can also pitch ideas in person, if you're lucky enough to bump into an editor at a party—or if you have an ongoing relationship with one.
The name of the game of in-person pitching is manners! You can get away with a lot, if you're charming, but cornering an editor at a social event can end your chances. Try to imagine yourself in her/his shoes, and behave accordingly.
Essential Questions of a Good Pitch
A good pitch is short and should answer three essential questions: Why me? Why now? And, so what?
Convey to your editor why you are the right person to write the piece that you are pitching. Your pitch should explain your expertise in the subject area, and give your relevant credentials. An editor most likely will not want to see your entire resume—the jobs you've held aren't relevant, unless they give you a foundation in the subject matter you're pitching. A few lines in which you sum up your experience is enough.
For example, if you're pitching a piece on peacekeeping in Darfur, you might explain that you are a former UN human rights observer who has worked overseas in various missions, and written a book about the experience (Kenneth Cain's article).
Or if you are writing about Rohingya refugees in Bangladesh, you might want to include the fact that you have conducted your own field research on the subject (Kristy Crabtree's article).
If you're pitching a piece about women and popular culture, you might say that you've written a book about a fairy tale heroine who looks at ideas about women and sexuality over five centuries (Katie Orenstein's op-ed).
Tell your editor why a given piece is relevant and interesting at this point in time. Usually you'll cite a news hook or anniversary. For example, a piece on race and education might be pitched on the 50th anniversary of Brown v. Board of Education, which is the landmark ruling by the US Supreme court that declared having separate schools for black and white children is illegal (in fact, many such pieces ran that year).
You can also cite a trend: In "Muslim Women Could be the Key to Ending Extremism," Sahana Dharmapuri references a number of stories and images in recent American media, which contribute to the problematic fact that since "Americans have so often seen Muslim women as silent victims ... they probably conjure picturesque images of shapeless and silent figures in bright blue burqas as synonymous with 'Muslim women.'"
This is the most important question. You need to be able to convey to your editor why the piece you're proposing matters. And matters to a wide swath of people.
You can't rely on the fact that an editor will see the importance of a niche topic like, say, "Little Red Riding Hood," or the significance of your ongoing obsession with, say, an airplane crash from 1996.