Honestly any local org would be a good place to start. Even better if they have a social event where you can meet folks first. And it’s totally fine if you don’t want to continue with an org for any reason. Just find another that’s a better fit.
But if you’re looking for left or socialist orgs specifically, folks have already mentioned a bunch of good options: FRSO, PSL, IWW, etc. I know the IWW has regular organizer trainings, and I found that really helpful for getting exposed to and practice with organizing techniques.
Honestly any local org would be a good place to start. Even better if they have a social event where you can meet folks first. And it’s totally fine if you don’t want to continue with an org for any reason. Just find another that’s a better fit.
But if you’re looking for left or socialist orgs specifically, folks have already mentioned a bunch of good options: FRSO, PSL, IWW, etc. I know the IWW has regular organizer trainings, and I found that really helpful for getting exposed to and practice with organizing techniques.