Hey Gus, here is some quick info for ya.
Rule Of Odds
The rule of odds states that by displaying an odd number of objects, there is always one in the middle that is "framed" by the surrounding objects. This adds comfort to the artwork and is used in advertising quite often.
Simplification
Images with clutter can distract from the main elements within the picture and make it difficult to identify the subject. By decreasing the extraneous content, the viewer is more likely to focus on the primary objects. Clutter can also be reduced through the use of lighting, as the brighter areas of the image tend to draw the eye, as do lines, squares and colour. In painting, the artist may use less detailed and defined brushwork towards the edges of the picture.
Lighting Focus
In photography, one approach to achieving simplification is to use a wide aperture when shooting to limit the depth of field. When used properly in the right setting, this technique can place everything that is not the subject of the photograph out of focus.
A similar approach, given the right equipment, is to take advantage of the Scheimpflug principle to change the plane of focus.
Scheimpflug:http://en.wikipedia.org/wiki/Scheimpflug_principle
Geometry and symmetry
The "rule of odds" suggests that an odd number of subjects in an image is more interesting than an even number. Thus if you have more than one subject in your picture, the suggestion is to choose an arrangement with at least three subjects. An even number of subjects produces symmetries in the image, which can appear less natural for a naturalistic, informal composition.
Related to the rule of odds is the observation that triangles are an aesthetically pleasing implied shape within an image. In a canonically attractive face, the mouth and eyes fall within the corners of the area of an equilateral triangle.
Other Techniques
* There should be a centre of interest or focus in the work, to prevent it becoming a pattern in itself;
* The direction followed by the viewer's eye should lead the viewer's gaze around all elements in the work before leading out of the picture;
* The subject should not be facing out of the image;
* A moving subject should have space in front;
* Exact bisections of the picture space should be avoided;
* Small, high contrast, elements have as much impact as larger, duller elements;
* The prominent subject should be off-centre, unless a symmetrical or formal composition is desired, and can be balanced by smaller satellite elements
* the horizon line should not divide the art work in two equal parts but be positioned to emphasize either the sky or ground; showing more sky if painting is of clouds, sun rise/set, and more ground if a landscape