Build your own brand. YouTube or podcast. Pick an issue, create a format, knock it out. Repeat 100 times while improving along the way, and you won't need an organization.
Not to diminish the ambition here, but I'd argue that building a brand in the form of producing media on the issue doesn't do well for swinging minds to your side, particularly nowadays. Unless it's a matter of getting people who agree on your issues to act on them, broadcasting develops an audience of people that are the opposite of fallingsaucer's target. Think of campaign ads in an election.
You're right. I'm going to check out a political party and see if I can contribute that way.
Looks like it could be a way to get experience via volunteering. It will give me political connections for when I get my own organization up and running. I don't intend to do the vlogging thing anyhow; I don't have that kind of expertise. I merely want to contribute to a cause I see as important with the skills my psychology degree and experience has provided. There may yet be better options..