This is what I posted at Painting Friends re' composition:
"The very first questions to ask is: Why do I want to paint this?
If you can answer that question you are on your way to learning composition.
I wanted to paint the iris because I love purple and the greens in the leafs but it is more than liking the color. It was the translucent quality of the light petals, the deep rich purple that offered contrasts to the light petals. The yellow spice color at the throat of the lilac which is actually a complement color. It was the line of the elongated leafs versus the more broad shape of the large iris.
So when I painted this the main things I wanted to emphasize were these elements:
Shapes and Line - elongated versus broad, hard edge vs. lost/found edges
Color - purples with its complement of yellow and analogous colors of yellow-green through blue-green, putting in a warm spice color of the quin. burnt orange.
Contrasts - Dark next to light in the focal point which was the iris; hard versus soft; smooth vs. texture
So if I were to do this again, and concentrate on only one element, I would choose line simply because line can bring us to the essence of a photo or a painting and help us learn the subject matter. Take a Sharpie and draw on the photo. Look how the lines help give balance, interest and a directional flow of the subject.
P.S. When using line, this is where one can leave out, add to, mute or bring forward areas. It is all up to you. That is why thumbnails, quick sketches, marking the photo, all tools to help us see and learn."
One of the suggestions at the art group was to discuss and work with one element at a time to develop more understanding of that element and have it truly sink in to the subconscious. I think the first element to develop, as stated in the "P.S." will be line simply because we can see it, develop it, modify it, evolve what we see to what we can conceive or create.
If anyone wants to jump in with comments that will lead to more understanding of composition, please do. I will then post the comments in a post so they can easily be viewed.