How can I avoid the manual processing surcharge?

Almost all carriers follow the same packaging guidelines. All carriers stipulate that the item must be well protected by using a cardboard, sturdy package that is square or rectangular. The products should be secured in the packaging to prevent movement.

PostNL
The shipping label should be affixed to the largest side of the box and on the top right. For a detailed overview of what does and does not result in manual processing, we refer you to the (dutch) PDF where we explain this further.

DHL
DHL also has a page dedicated to providing packaging advice .

DPD
At DPD, this page  is available where they specify the requirements the package must meet. 

UPS
UPS's packaging advisor helps you package and ship your parcels according to the carrier's guidelines.