Traveling to Switzerland by plane
If you travel to Switzerland from within Europe, you can check whether the train could be an alternative to you. A transfer by train would make sense if it takes a day or less. Trains provide a comfortable way to travel, and the CO2 footprint is much less than a flight. You would help the Alps by doing so!
If you travel to Switzerland from outside of Europe, a flight is the way to get there. Still you would be able to compensate for the CO2 emission caused by the flight, as you can read here.
The major airports are in Zurich, Basel and Geneva, and there are smaller ones in Bern and Lugano.