Zig zagging is certainly a helpful strategy, and absolutly agree with keeping centre of gravity low and taking smaller steps. I'd also suggest facing your feet across the slope on steep loose terrain, and using the edges of your footwear to get traction. That tends to work best with heavier boots, but helps with shoes too. When it gets really steep, it can work well work your way down hill with small side steps, while facing your body and feet across the slope rather than down it. On firmer terrain (like rock slabs), instead of using the edge of your soles, face downhill (ankles tend to have a greater range of motion rotating forward than they do sideways) and try to get the whole of your foot flat to the ground. This ensures maximum rubber contact.
Also, keep your weight over your feet. The more you lean back (unfortunately a natural reaction) the more likely you are to loose traction. Trekking poles can help with this, by making you feel more stable, as can reminding yourself to keep your "nose over your toes".
Another trick which can help, depending on the terrain, is working from one stable zone to another. Pick spots on the slope that are slightly flatter or more stable, and deliberately set out from one to the next. This can help to break up a longer slope.
This terrain is not super steep, but the hiker is coping with the scree well.