There are psychological principles that can be studied and followed, to make things more understandable and more usable.

NORMAN, Donald, The Design of Everyday Things

Good designs do not just happen! They are the result of careful application of numerous design methodologies that enable you, as the designer, to understand the user, the environment, and how they interact.

KORTUM, Philip, HCI Beyond the GUI

It is ultimately experiences that we are designing, not things.

BUXTON, Bill, Sketching User Experiences