Imagining electric flux intuitively
Its been shown that a precise analogy (math solution, to differential equations) exists between electric fields in vacuum or air, and electric fields inside a conductive sheet of carbon_particle_loaded paper.
The constraint of the field lines is that at a highly_conducting surface, the field lines MUST ARRIVE at the surface at exactly 90 degrees (orthogonal to the surface). Any tangential component will cause lateral movement of electrons, causing re_arranging of charges at the surface, until orthogonal flux/field lines become sufficient to describe the field at the surface.
So draw thee some surfaces, and start sketching lines flowing between them,
Two surfaces at 90 degrees, such as two isolated metal pieces that (almost) form a corner, is good place to start.
I recall old versions of Schaums Outline had these sketches.