Tactical urbanism is a fast, cheap, action-oriented approach to making meaningful civic changes to neighbourhoods, towns, and cities.
Maybe you could...
Start a play street
Throw down some tires and spray paint a mural on an underused street to reclaim the space for pedestrians.
Put a bench where people need one.
Set a line of potted plants on a flared junction to narrow it.
Scatter some lawn chairs in an abandoned parking lot for a pop-up café.
Tactical urbanism if often done as a collaboration between citizens and local authorities.
Examples abound, and funding is available: see link to the Asphalt Art Initiative.