First, I want to educate myself as well as possible, both for my own convictions and for my ability to reason and defend the Jewish people from a Christian perspective. Second, we can carry these beliefs out to our family, friends, and church community. Third, I think we can work through our local churches and church governance institutions to advocate for fruitful interfaith relations between Christians and Jews.
Personally, I have engaged many friends on the topic of supersessionism and I think quite successfully so. A love for the Jewish people, or at least an understanding of the Hebraic worldview, is transformative to our faith and biblical understanding. I have found it to be doable at least to make people (re-)consider the notions that they have uncritically adopted on Israel and the Jewish people. We should, however, not be limited to our immediate neighbors, but rather carry this mission out wherever we find ourselves, including in politics, media, and education.