in order to make a soft landing, you need to reduce the velocity of the lander to less than 2 meters/second. how can you do this without wasting fuel

just add drag with the wings and turn them so it slows down but doesnt flip.

Explanation:

In the absence of thrust, the lander continues to accelerate downward. As it approaches the surface, use maximum thrust until you get the velocity near zero, then turn off force. Allow it to pick up downward speed and repeat briefly, as necessary. The most important thing is to not waste fuel by “hovering” in one place, or worse, going upward!