There's many ways, from benign organizing of protests or involving the media all the way down to armed insurrection or terrorist threats. Again, you're a protagonist - choose your own story!
Then there's Ghandi, the Arab Spring, Milošević, the Iranian Shah as examples of things going the other way - and those are just the ones that immediately came to mind.
Again, don't be a bystander believing in foregone conclusions - that way you make them self-fulfilling prophecies. Be part of writing the story instead!