Do not carry ice cubes - drinks are already cold.

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.

If possible, adjust aircraft speed to reduse fuel consumtion

Incentivize sustainable behavior, e.g. a small reward for bringing your own coffee cup. This can also be sold by SAS in the Eurobonus store or in flight.

Finger food that's easy and clean to eat reduces the need for cutlery and packaging. That's less weight and packaging and opens up for fun, hearty snacks.

Go for a fast integration of programs, joint schedules to increase cabin factors in the SkyTeam system - so passengers stays in SkyTeam which will also benefit SAS.