You need real-world mentorship. There are basically two ways to get it. I suggest the second one is better but it's okay to do the first.
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Apply to organizer positions at unions, i.e. become paid staff. 98% of the time these positions are designed to burn you out and there are 5 low-level organizer positions for every next-position-up. But you will learn the skills (for a staff union bureaucracy at least) and make connections.
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Join a local active socialist or anarchist group that specifically organizes unions. Not all of them do. This requires more care and skepticism because sometimes these groups are far more effective and useful than staff unions and sometimes they are fairly useless and lack constructive self-criticism. Identify the people in them that have a track record of success and prioritize their opinions. They will be the ones trying to organize the others in the group.
The key advantage of the latter is that they are volunteers and will take on the organizing efforts that are pioneering or neglected. You will not face distractions of careerists and climbers and everyone will be committed and organized rather than afraid for their status and paycheck. This will give you a stronger core. You will also make connections this way.
I can't recommend specific groups because they vary wildly by locale.