Lisa next time you meet a Jew or Jewess who says Tikkun Olam to you, you ask them what does that mean? And ask where does it come from? (I assume they will say from Judaism), so you say that Judaism comes from G-d, thus it is G-d who defined Tikkun Olam. Tell them next (not necessarily aggressivly or argummentivly) that since G-d defines how to make the tikkunim to the world, to the individual and actually to all the world's then why aren't they doing the Tikkun olam the proper way by following the way G-d has defined it? (They will say, but we are- look we are voluntering for this or that), and you can say that the proper way in doing what is right is how G-d defines what is right and wrong, they can start by learning Torah to know what is right and wrong to be done (and by the way, is one of the biggest Tikkun Olam that we can do becuase each word of Torah is = to all the Mitzvot combined). - Of-course you can show them different good sites to check out- (I suggest Rav Mizrachi first- definitly will bother the conscious at first and make one have it stay in the mind long time that will then encourage furthus investigation and then G-d willing to the true Tikkun).