Asklemmy

Not knowing where you are, it's hard to say. But you might as well start with whatever is most accessible to you. Getting involved will help you get to know who's doing what and how in your area. I will say it's usually easier to move from less to more radical groups than the other way around, so if you're shopping around, you might want to start with a more mainstream group.

Just an idea: have a look in ask Lemmy or no stupid questions for posts of people who have asked similar questions in the last 12 months or so. How to bring about change or how to start a revolution has been asked. In those posts you'll at least find another user who is thinking along your lines. There may be more in the comments. Reach out to them.

Usually through sexual activity, be it solo or with friends and family

The best way is to be a charismatic leader who draws people to your cause.

Revolutions aren't started by people joining groups and building committees. They are started through cults of personality (for a person or a thing).