If you spend any time at all in Content Marketing circles, you’re going to hear about Jon Morrow. He’s brilliant, and he has put together a free e-book on headlines that he calls Headline Hacks.
It breaks Headlines down into some of the most effective forms available, and when I’m writing headlines, I’ll often pull up the PDF and look through the formats he uses. They’re particularly useful when you have an idea of what you want to say, but you can’t quite put your finger on the right angle to take. Looking at potential headlines is a great way to figure out how to tackle a subject.