As far as living in Guad, isn't there a large community of expats in GDL? Perhaps that might be a way to meet people in a very large city, although you'd be meeting other expats, but at least it might provide some social activities and a way to meet others. There must be organizations or clubs or places where expats meet and socialize. Maybe these are listed in a GDL newspaper or online or on other forums. I realize that interacting with other expats may not address the issue of meeting locals, etc. But it might be a place to start for someone without a lot of connections to the Mexican society in a large city.