If you want to make a difference, don't practice what you preach
Rather, preach what you practice. You'll make a bigger impact. When you talk (preach) about what you're doing (your practice), you're already doing it. So it's obvious to others. When you practice what you're preaching, you're first talking, then doing... assuming you actually get around to it.
Most of us have heard the old saying, "actions speak louder than words." I mean, how many times have you given your kids, your spouse, yourself some version of the stop-talking-and-start-doing-it speech? Hey, even fictional sports agent, Jerry Maguire, learns quickly that words are just not enough when his client demands proof of his promise: "show me the money." But maybe the Nike shoe company slogan says it best: "Just do it!"
Making a difference isn't really all that hard to do. Simply make a conscious decision to take a stand on something and then align your actions to those that accompany that belief or ideal. For example, is honesty important to you? Be honest yourself. Want to see more patience, compassion, or kindness in people you deal with every day? Exhibit those qualities yourself. Instead of being quick to complain or criticize (yes, even silently), clear your mental view of intolerance and negativity, and focus on qualities of good that are surely present. In the words of famous anti-war activist, Mahatma Ghandi, "be the change that you wish to see in the world."
Christ Jesus, master healer and humanitarian, and arguably the most influential man to walk the earth, said "by their fruits ye shall know them" not by their enticing words. If you want to make a difference, your fruits will speak louder than any number of words could ever be preached.