In fiction, the main areas that a structural editor will address are:
Plot
Does the plot make sense? Is it believable? Is it satisfying or does it leave the reader frustrated?
Themes
Are the themes effectively handled? Are there so many that the book lacks focus? Do they interfere with the plot or complement it?
Characterisation:
Are your characters well developed and believable? Are they cast in a role that fits their personality? Do they sometimes behave out of character?
Point of view/voice
Is the voice consistent or is it sometimes confused? Is the voice authentic? Are you using too many or too few POVs?
Pace
Does the plot move forward at an appropriate pace? Should you cut that preface? Should the action happen sooner or should the tension build more slowly?
Dialogue
Do your characters sound real when they speak? Is your dialogue cluttered with adverbs and beats? Do you use clunky dialogue to move the plot forward?
Flow
Is the narrative interrupted by dead-ends and tangents? Is there so much back story that the main plot is dwarfed? Are there missing plot points that would give the narrative greater integrity?
In non-fiction, the principle is similar but will look for continuity, consistency, completeness, thoroughness and focus.
