Reflex to have upon receiving your package regardless of the carrier: Take the time to examine the condition of your package and your goods.
If either or both seem damaged, opened, repackaged by the carrier, you can refuse the package or accept it while issuing reservations.
Example: product xx, brand xx, damaged and scratched on the side, 1 product xx, brand xx missing out of xx ordered, etc. Be as specific as possible about the type of damage on the type and number of products because carriers may sometimes refuse reservations if they are not precise enough.