Connect with an organization like one of those below
Here are a few organizations that are in multiple geographic locations and connect people to multi-racial, working class organizing. Ideally, look for chapters that are located where you can physically meet with others and build relationships rather than simply signing up for online actions.
Working Families Party (welcome gatherings here)
Showing Up for Racial Justice (chapters here)
Movement for Black Lives Action Fund (scroll down for local organizations)
Reproductive Justice organizations such as those listed here. (Note that the Reproductive Justice movement is much broader than just access to abortion. See this definition and herstory from SisterSong)
And many more (feel free to suggest more networks in the feedback form)
You can also explore the breadth of what organizing can do to make an immediate difference in communities by listening to episodes from the podcast One Million Experiments, which showcases organizing projects from around the country.