Fill up empty seats by selling affordable return trips to unknown/secret destinations. Pick the destinations among those that have low occupancy close to departure time.

Mount small blades on the side of the wheels to make them spin by themselves before landing to reduce tyre wear upon contact with tarmac.

For hand wash tissues, hand out from a larger container instead of singles wrapped in plastic.

On your flights, start sharing how much of that flight is powered by biofuel purchased by customers flying.

Change plastic luggage-trays at fast-track for sustainable (but durable) trays of reused plastic or other cyclic material

Travel light = bring less than 8 kg. If you do so, you should be rewarded with points. If not, SAS will use the extra money you have to pay for sustainability investments.