Tomboy esthetics depend on appearance as a whole. Pose is important aspect in the expression. Poses with shoulders swaying back and hips forward -- the opposite of the feminine 'straight' pose with bosom forward -- seems particularly important.
Silly face, cool glasses and use of reflection, clean lines, great natural light ----- this is one of my favorite portraits i found on here. i love the reflective glasses and the composition. i dont even know why but its just fun and edgy