When you're pitching a writer for the first time, I've found it's best to keep it short, focus on the story (show them the angle), and make it clear you just aren't blasting a bunch of writers. I usually try something like "Hey I'm the cofounder of BY. We just launched a product that helps people improve their own search results without having to spend thousands of dollars on a reputation firm. For example, my co-founder Pete couldn't get an internship in college because he was being mistaken for drug dealer and couldn't afford 7K to fix it. I read some of your posts on online reputation (link to them) and thought this might be a good fit. Let me know if you're interested--have plenty of details if you want to know more"
And yes, once you establish that relationship it becomes easier to tell them about an upcoming story. Even then, you want to keep it short, and focus on the story for them so the hard work is already done. "Hey, we just released a new feature. We can actually tell you when an employer googles you or finds your profile. For example, say you're interviewing at ad agencies in NYC, you might get a alert that says someone from Ogilvy just Googled your name and found your profile" We're really the only place providing this intelligence, let me know if you want more"