Back when I was in college in a Christian organization we would pair up and go share the gospel with other students on campus.

One technique that worked surprisingly well for me was that one of the pair would pick the person that the other would have to go up to and try to converse with.

Somehow that created the feeling of a dare that I could get into, even though if I had been considering talking to the person on my own, I would have talked myself out of it.