Join a group at your school or in your community that is dedicated toward alleviating some sort of social distress. This might be a known group, like Amnesty International, or it might be a group in your community, for example, to help repair cars for people who do not have money.

Perform an Internet or library search to understand diversity in your area. What kinds of diversity are there? What are some things that the different groups hold in common?
What are some points of difference? Are there particular issues that require dialogue?
Brainstorm ways with your friends to start such a dialogue or to join one, if it is already in progress.