Just don't do things that are absolutely not sustainable...

Sustainable meaning: if everyone does this we need 5 planets...

The good news is that with technology there will be fewer and fewer of those...

But if you really wanna minimize / lead by example you could live in a small appartment in a big city... It's the most sustainable way to live. Besides that help improve / maintain the common infrastructure... Libraries Swimming pools Toolsheds / Makerspaces Schools Etc etc

A tiny garden at your home < a big park and shared city vegetable plots Electric bicycle for 80℅ of your commutes and share / rental car when needed. Getting rid of stuff you no longer need (helps with living in a small place as well)

Countless little big things.

Also: - buying second hand phones - investing in solar projects -...