A tweet is a headline

Some of the most talented (and well-paid) journalists are the sub-editors. They are the ones who prepare a story for final publication, and often create the headlines. In the world of marketing, headlines are also critically important. As the great David Ogilvy put it "On the average, five times as many people read the headline as read the body copy. When you have written your headline, you have spent eighty cents out of your dollar." Here's one of his gems; "At 60 miles an hour the loudest noise in this new Rolls-Royce comes from the electric clock."
 
I believe the same principles that drive great headlines also apply to effective tweets. They need to be brief (obviously), eye-catching, enticing and ideally humorous too. Often, you will be using a tweet to encourage people to click on a link to an article or blog post. I suspect that the click-through rate is rather less than David Ogilvy's one in five, so you need to think carefully about what you say. 

Obviously, not all tweets need to be carefully crafted. Some are just "of the moment". But for those that include a call to action, take a while to pause and think how they would work as a headline, and whether they appeal to the audience you are trying to reach.