As far as I can see, a style is the systematic repetition of decisions regarding art elements (a.k.a shapes, values and colors).
Ok, there's a lot of information here. Let's first make sure we understand ourselves when we talk about art elements. Then we we'll talk about the visual decisions we make when creating an image.
This first part may sound very basic for you, but bear with me as I try to find some common language with everyone reading this.
Visual art is generally broken in: dot, line, shape, form, value, color - some people would also add texture, space, rhythm, composition and a few more.
On a daily basis I get myself mostly thinking in 3 of this: (1) SHAPES, (2) VALUES and (3) COLORS.
I may not be the most reliable source on this, but here's a 101 about shapes, values and colors:
(1) SHAPES - The most simple elements of visual representation are dots and lines. Whenever you organize dots and lines in "perceivable chunks" you start to have shapes. They can be organic or geometric, simple or complex, they can represent form tridimensionally (rendered in 3D) or bidimensionally (flat 2D). Shapes can also be organized in a canvas in order to imply rhythm. Lastly the absence of a shape can form a shape in itself (see the 4 circles/ 1 star example bellow).
(2) VALUES - They are all the grey range between pure white and pure black. Imagine you take away all the hues of an image, all that is left are the black, greys and white values.
I tend to organize images according to the use of values in 3 ways.
a) They can be high key (most values are closer to white), low key (most values are closer to black) or use the full range.
b) They can be high contrast (only a few grey areas) or low contrast images (most image is grey, with few whites and darks).
c) They can be organized to simulate lighting or not.
(3) COLORS - These are all the hues that make up the color wheel. They can be saturated or desaturated and always work together with values. They can be organized in hot or cool colors. They can also be arranged in color palettes (this palettes have different names depending on the colors position in the color wheel - Complementary, Analogous, Primary, Secondary, etc). Never forget that colors are not perceived independently, they always suffer influence from the surrounding colors.
