Selling your ideas takes passion, preparation and perseverance. You need to listen first to build rapport and prove you don't have all the answers. Then bear down and deliver a seamless argument that's tough to counter.
Citing evidence strengthens your position. If you're tempted to talk in generalities, consider Albert Schweitzer's advice, "Example is not the main thing in influencing others. It is the only thing."
Speaking of the power of example, persuade by modeling what you want—by serving as a living, breathing example. In the words of Ken Kesey, "You don't lead by pointing and telling people some place to go. You lead to going to that place and making a case."