I feel as though a lot of these suggestions might seem repetitive, but I will say again that there really is benefit in dealing directly with community groups, because a lot of individuals, particularly recent immigrants but even individuals who have been here for several decades, are very tied to their community. There are a lot of cultural centres or community groups or community organizations that these individuals dedicate significant amounts of their time to. Through that you have the magic of word of mouth, so to speak.
I think working intimately and directly with those community groups, putting in the effort to try to identify who the community leaders are, where these people are going, how they are spending their time, and then reaching out to those cultural hubs, is one of the best ways to communicate information, even more so than social media.