The 1st chapter in "Made to Stick" by Chip Heath and Dan Heath talks about one of the key elements of making a message stick: simplicity.
Simplicity: find the core of the idea.
Some of the ideas mentioned in this chapter:
Commander's Intent (CI): In the military, it's "a crisp, plain-talk statement that appears at the top of every order, specifying the plan's goal, and the desired end-state of an operation."
Finding the core=stripping an idea down to its most critical essence. You not only have to weed out the superfluous and the tangential, but also the things that are really important, but just aren't the most important idea. The value of the CI is its singularity.
In journalism, reporters know not to bury the lead. The first sentence of the article, called the lead, contains the most essential elements of the story. After the lead, information is presented in decreasing order of importance. This is known as the "inverted pyramid" structure. This is great for readers. No matter what the reader's attention span--whether just reading the lead or the entire article--the inverted pyramid maximizes the information gleaned. Finding the core--writing the lead--creates forced prioritization. If you can only send one line before the line is cut, what do you send?
Great simple ideas have an elegance and a utility that makes them function a lot like proverbs. Short sentences (compact) drawn from long experiences (core).