Firstly, a fresh and objective listening of the sound, and a subjective optimization of the music.
High quality monitors and D/A converters, with a good acoustic in the studio, to have a high fidelity of how it really sounds.
Experimented, trained and specialised in mixing to listen and enhance sounds.

I chose to specialize as a mixer, cause I just like to listen to music and play with it to make it even more enjoyable.