That picture shows a good start. Not directly illuminating the sky when the illumination is being used on the ground is the low-hanging fruit, but additional measures should be considered:
* Use light of lower intensity (candela) to put less illuminance (lux) on what's being illuminated. This is a more precise version of "use a dimmer light", because reducing output (lumens) won't necessarily do that if the light is more focused/directional.
* Illuminate fewer places. Street lighting for traffic safety doesn't need to be everywhere; it needs to be where hazards are.
* Use alternatives to general illumination. Some road hazards can be marked with reflectors or low-intensity marker lights pointed directly at drivers instead of overhead lighting.
* Turn off lights when not in use. Use timers. Use motion sensors. Use buttons pedestrians can press for crosswalks.
* Encourage people to use portable lighting rather than fixed lighting. This becomes more effective when there's less ambient light because less light is required to achieve the same contrast with a faraway background.