Make it easy, make it personal, make it salient. It's not rocket science, it's somewhere between common sense and psychology 101, and that goes a long way.
RICHARD H. THALER is the father of behavioral economics the study of how thinking and emotions affect individual economic decisions and the behavior of markets. Thaler is Director of the Center for Decision Research at the University of Chicago Graduate School of Business. He is coauthor (with Cass Sunstein) of Nudge: Improving Decisions About Health, Wealth, and Happiness.