Talk to the people you want to be in your community.
If you can’t find the people you want to reach, if you can't get them to respond when you message them, if you can't engage them in a sustained conversation – what chance do you have of building a community from these people?
I've seen dozens of online communities launch without ever having spoken to the people they're trying to reach. That's a lot of time and money to lose because you didn't take a few hours to talk to potential members.
Communities wont work if the prospective members are closed to new things, uninterested in talking to each other or too busy to even acknowledge something new.
The first thing you should do, when you want to start a new community, is try to have conversations with the people you want to reach.