Union meetings are probably the most valuable approach because you end up organizing with people you interact with on regular basis and you can build deep relationships with. My experience is that people protests don't really have a high conversion rate, and they tend to be more of spectator events. But I'm not going to discourage people from protesting obviously. There is value in visible public demonstrations of discontent, and it helps people know many others share their grievances. It is a tool that helps combat alienation somewhat.