Organizing is a skill in of itself. It must be learned and practiced until it becomes almost second nature. This is one of many reasons why labor unions serve as a "school for communism".

A big part of organizing is convincing people who are not already "on your side" so to speak. When a union campaign first begins, many workers are actually against the idea. Organizing is a process of convincing these workers to cast off their previous assumptions and recognizing their power as part of a larger union. They need an "aha" moment that often comes from some collective action taken together.

I recommend reading through No Shortcuts by Jane McAlevey. The author is not a Marxist, but organizing is not a skill exclusive to Marxism. ProleWiki also has resources on organizing that I'm sure are excellent.

Edit: As an aside, organizing is also hard, maybe the hardest thing you'll ever do. It takes listening, openness, and patience that will test your temperament. But remember that we're all workers, and we can find common ground through our common class interests. Our eventual succusses will materiallly improve people's lives, and they will build (despite setbacks) until we can ultimately institute a socialist society.