If there's no union in place there should be. Which means joining a relevant union and trying to recruit others. Which of course might identify that the management is anti-union, which is the kind of job where you really need a union.

The same laws that give people a right not to belong to a union give a right to union membership. In any job. There are some countries which don't have that, and some employers who break the law blatantly. Everybody has a duty to fight that if they come across it, even if they don't want to join a union themselves.