How to organize resistance against authoritarianism?

Hello,

The political situation in the US is rapidly declining. The tariffs imposed on Canada and Mexico mark a definitive moment of objective insanity.

Given resistance to these tariffs has massive popular support, there is a rare opportunity to organize protests, however I have zero experience in doing so and there are few large preexisting support networks. Those that do exists are essentially limited to workers unions and wouldn't help us.

How do I organize a network? What have you learned from experiences protesting in Croatia?

Thank you so much!