I will not promote, but how did you promote?

I will not promote. That said, how did you promote your C2C business? My target user is a parent, especially moms. I got some traction from Facebook groups, but they are what they are. How do I reach more users? I am currently focused on one region, just NYC. What are different channels? I'm thinking I'll print flyers and go to all the buildings in my neighborhood. I know that's not efficient, but I need a start somewhere and the business model is hyperlocal.