I think presenting real life cases would be helpful. Some people think that will never happen to them, but it can and does. I have a friend who might come. She regrets not doing a certain vax because of how the illness affected her child, and she has changed her beliefs just like I have.
Talking about how the immune system works will be good too, as that is not something I came across when I was researching.
In my opinion, face to face would be BEST. If you can get people to meet at a certain time somewhere, that would be best because then the communication is most effective for those people, who can then bring it back to other people they know, if that makes sense. Sending it out over FB, Twitter, blogs, etc, should be secondary as follow up. With something like this, I really feel that you have to start small and local and make a difference in a few before reaching out to many.
With good information, you may be able to dispel some myths in some people. One person at a time can still make a difference. Don't feel bad if 20 people go home without having changed their minds but one person goes home and gets their kid vaxxed. That is still success. :)