Since that piece went live, a funny thing has happened: several faculty and grad students have dropped me emails asking for advice on how they too could maybe write for a popular audience. It's easy to forget that--for all that academic training--communicating with journalists and editors, and writing for the educated masses, actually takes some reframing of perspective and and disciplinary behaviors. In fact, writing and speaking for a popular audience has taken a damn good bit of unlearning what grad school and the academy has taught me.
So! As I've been answering this question alot for friends and colleagues, I thought I would just compile the advice I've been giving out and post it here for everyone's benefit. No guarantees implied, but hopefully you'll find this a helpful place to start.
1. Whenever Possible, Flex Your Network to Find a Point of Contact (Get a Network)
Even imagining that I could write for The Atlantic would have been much more difficult if I hadn't had a friend who is a journalist who was able to give me a direct introduction to The Atlantic's Tech Editor at the time. It was actually a conversation we'd been circulating around for months, when we would run into each other at events. I felt very intimidated by the idea of writing for a popular press, and her intermittent encouragement went a long way.
Obviously connections like these are harder to assemble (or outright impossible) if you don't live in a major metropolitan area. But you'd be surprised what asking around does. Maybe someone's brother or college roommate or old LiveJournal friend works in a field or for a venue you're interested in. Think out loud, don't limit your professional contacts to academia, and know nothing bad comes from asking for what you want. Also, lots of academics have pursued alt ac careers in journalism; maybe spend some time figuring out who those crossover folks are, and how you can be of service to them.
And the worst case scenario? You do a cold pitch. See below.
2. Get out of the academic rejection model mindset
Peer review, job searches and conference submission can make a meat grinder of self-esteem. We're conditioned to believe our ivory tower gatekeepers want to dislike your work, so they move quickly to the next application. Dr. Karen Kelsky even has some great wisdom on coming to grips with this reality of academic employment.
I once explained this reality to a friend who was an actor. She told me the audition process couldn't be more different. "They want to love you. They want you to come in and be the person who makes their play come alive." (It doesn't mean you'll get the part, but still.) It was a powerful conceptual shift.
I've come to learn the online journalism world has a touch of this too. Any major outlet has to produce so much content, every day, over and over again. They want to like your pitch. They want you to be the next smart person to make their life a little easier. This isn't the stern face of peer review, and there's no cruel hierarchy games here.
3. Act like a professional, not an academic
Academics are prone to wordy emails, CV recitations for intros, and verbose explanations (my inbox is proof!). Especially if you're making that cold pitch, avoid overburdening the first point of contact. Keep intros succinct and get directly to the point. I would recommend that the opening inquiry email contain 3-5 sentences on the idea, and ends with something like "If this sounds like something that would be at home at [this venue], I'm happy to expand this into a formal pitch." However, do your due diligence: some sites have very specific directives about how they want pitches to be made or submitted, so look around on the website first. From there, it's just feeling out the relationship with the editor. I wouldn't expect a pitch to go over 2 paragraphs (mine didn't), but your editor knows best.
4. Be clear with yourself about the "big idea" and what you can accomplish
A popular press venue is not a space to make academic arguments--no matter how dashing that argument may be. You can't use footnotes or cite references. Just own your knowledge and have a big, juicy idea. If there's a subtle point you want to prove, I always think it's sexier to show rather than tell. I've also learned that online writing favors smaller paragraphs and shorter sentence structure. In most cases, it's wise to take your editor's notes and corrections--they actually do know more than you in this arena.
My friend in journalism, who I mentioned earlier, gave me some nice perspective on how to think about the audience and the writing: at the end of the day, you're giving someone a provocative, new topic to discuss with their friends at brunch. That doesn't mean the work is shallow. It means you have to be an ally to your reader, and create an inviting space for them to explore.
Go forth and have readers!