What actionable steps can you take to build community?

Obviously this is a broad and controversial topic (especially since I'm asking about both on and offline) but as individualism and isolationism seems to be increasing in the western world, I'm wondering what can be done and what others have done to counteract this trend.

Edit: Obviously, there's broad things like participating in hobby groups or being nice to neighbours, but I'm especially interested in discussion of specifics, such as ways to set up these groups, organisational structures, or ways to expand connections from a hobby group beyond just the hobby.