It often helps top look at something far away or squint to determine the compositional motifs - the composition of a piece should be its simplest parts boiled down without the details. If a line is too complex, we sometimes lose interest. Certain lines are dynamic. Others are static. 8. light - bright or dark, illumination.
Light can either be 'on' a surface or 'through' a surface.
It can be lucid and ordered or confused and cluttered. Think of recession in space, use of parallel converging lines, vanishing point perspective, and even perspective with more than one vanishing point. Think about possibilities of arrested movement, implied or suggested movement. For terms and usage, look at David Piper's Looking at Art, Random House, 1984.