Forces push and pull - every aspect struggles against one another to find its place in the picture.
Years ago, the Greek idea of the hero's journey was recapitulated by Joseph Campbell in The Hero with a Thousand Faces as a way to understand myth and fiction; it can also be related to painting.
Regardless of whether the work is abstract or representational, the elements of narrative can be explored in a painting.
Some of the main conflicts well known to drama are: Man against Man, Man against Nature, Man against Himself, Man against God, and Man against Society
Something has driven you to begin your new work, a need, a calling: a line is drawn, a color placed, a series of marks made - soon the dominant elements show themselves like a series of characters in a story, each striving toward a goal.
Often, successful narratives and paintings have one element or character that is most important or dominant - the hero.
I like paintings that leave some of the early and middle stages visible to allow the story of its creation to unfold. Every artist prefers varying subject matter and different levels of finish or completion; however, keeping in mind the parallel components of visual design and fictional narrative can enrich a work of art with multiple levels of interpretation.
Each character is striving toward some goal - they have a need - and by struggling to accomplish that goal and satisfy their need, they experience growth - a character arc.
The hero has a call to action - there is a reason to step forward, to do something, to draw the line or place the color. The situation is considered, and troubles and challenges accepted - the hero must question himself and any doubts: as in literature, specific engagements are purposefully employed to explore and express these trials. The hero chooses - or is driven to pursue the outcome, regardless of consequences
Parallel to your thoughts about design principles, consider each of the elements as individual characters striving for authority and resolution; if you can sense the symbolism and metaphor, it can help with unifying elements across the canvas.
Let the paint speak for itself and you'll find it has its own truth, force it to say something and you may find that all it can do is lie.