Fourth, he should talk about the dangers of inexperience and the dangers of unblinkered ideology—so that he can show that he's not an ideologue, because he's not. The nation is tired of big dreamers and big talkers. It doesn't want a freedom agenda, or a "New New Deal." It wants to be strong again. It wants to have a growing economy again. It wants the government to be small and effective again. It wants America to be humble in ambition, and ultimately, only as strong as its people. He should say something like: "Every four years, Americans are promised lots of things. Big things. Promises that nobody can keep. Like cooling the oceans. America will always have new challenges. And we'll always meet them, as long as we have a strong economy and a free people. So tonight, I'm going to make you a promise I can keep: I promise you that in four years, we'll have those things."
Finally, he should move beyond platitudes and familiar appeals to Americana. He has a tendency to speak in generalities. But here's the thing: He has probably learned more about America in the last eight months than he ever thought he'd know. He has seen, up close, the frustration that Americans feel. He's heard them with his own words. He should sit down with his speechwriters and say: Here's what I saw. Here's what Americans are telling me. Here's what they want us to do. Don't focus group this speech. Use the language of people who know what this election is about. Americans know that Mitt Romney is a smart guy and a successful guy. They just need to know he hears them.
In full disclosure, I worked as a speechwriter for Romney in his 2008 campaign, and I didn't give him this advice then. I don't think it would have worked then. It might work now.