There is not a lot ot tension before and after the slap. By drawing the linę between the neck and shoulder in a natural position, you can express a natural, neutral body position.
The hair swinging creates the sense of being suddenly slapped.
back-and-forth (multiple) slaps.
You can draw a pose where the character's waist doesiYt twist b. I making the central lines of the body straight.
Twisting the waist makes the character look like she is accustomed to slapping people.
Not twisting the waist and having the character slap creates a mood.