Even though I work for Wired, I'm a writer not an editor, and out of the loop when it comes to freelancers getting assignments. Just so you know.
That said, I agree with Brandee's comments,especially about knowing the editor to whom you pitch. But I can add a couple of things.
First, keep in mind that we have a long lead time. The stories we do must hold for a whille yet still be compelling at the moment the reader sees it. You have to conceive of the story as something of lasting value.
Also, if you are not already known to Wired's editors, your best chance is to come up with an amazing story that we haven't heard of, and show that you are well positioned to do a great job on it.
If that sounds obvious, it's because there's no magic formula, at least none that I know of. But like every magazine I've ever known, we are hungry for someone who can deliver a fantastic story, and when one of those does come in, everyone is excited. And the writer is certain to be asked for more.