Unionise, strikes, mutual aid, and other forms of collective action that leverage the power of a group of people to their benefit.
Fights though? Where did you get that from?
Community defense isn't about "doing fights" and nearly anything else you might mean is just adventurism (bad)
We need infrastructure, General. Making a revolutionary army is the job of communist party, not militia adventurists or larpers. Jumping to "revolutionary" violence is putting the cart before the horse. If you want to shoot guns, join an SRA branch or whatever. If you feel like your only use is killing people, seek counseling.
Yes, but just getting a little group to do terrorism is counterproductive. What we need to do is support a ton of people with collective mechanisms so they will support “our” principled party that can lead them to victory over the bourgeois state.