Individually:

• Do a personal carbon footprint assessment. This will tell you what to focus on, if anything. I think the current mean footprint in Switzerland is around 12t/person/year. We need to get down to 1.5t…
• Do the necessary changes: insulate your house, renounce plane travel and meat, see if you can improve your personal transportation by getting an electric bike, public transport, moving or, if all else fails, getting a small electric car.

On a political level:

• Continue investing in renewable energy and/or nuclear
• Create an efficient carbon tax, ideally together with the EU
• Enact restrictive regulations, forbid certain wasteful activities or goods, limit the size of cars, mandate performant new buildings, etc.