Always wear both shoulder straps rather than slinging it on one shoulder.
Adjust the shoulder straps, so the backpack is high on the back and the shoulder straps are comfortable on the shoulders.
The backpack should not sway from side to side as you walk.
Children should carry no more than 10% of their body weight in their backpack.
If the backpack has a waist strap, it should be used. Waist straps distribute the weight load to the hips, relieving shoulder pressure.
This work commuter is wearing his backpack correctly.