Go out of your way to do stuff for other people.
I coach soccer for high school age kids. Every time I get the chance, or they ask, I tell them how much I love my sorority, and how there are so many stereotypes out there... I'm living proof that not all sorority girls are beautiful, sex-loving, alcohol-bingeing, college-age wastelands.
Some of them even plan to rush, judging by what I've said. Little things like that make a difference.