Use tech and services outside the big tech. Just Fedi over standard social. Use Peertube instead of Youtube.

Run Firefox.

Set up your own servers for yourself or start a community. Matrix, Mastodon, Lemmy, etc.

Run SearXNG as your search or help others by hosting.

If you can work of free and open source code that helps decentralize and give the power back to the people or create something new. Even if you can code, learning a project and helping others with it or helping create docs, etc.

Spread the word, but don't be annoying. Help less technical folks get decentralized.

It's very difficult and can be disheartening, but you don't have to cold turkey all of it. Each drip in the bucket helps until we're all united and become a tidal wave.

When all the power is centralized that's when those central players think they can do whatever they want.