The principles of design in art describe the fundamental ideas about what makes a piece of art good. A definitive list does not exist, as art is subjective and what appeals to one person or artist does not necessarily appeal to the next. Some common ground on the principles does exist and most lists contain center of interest or emphasis, balance, harmony, unity and opposition.
Center of Interest or Emphasis
The area that the eye immediately focuses on when looking at a piece of artwork is the center of interest or emphasis. This center of interest keeps the painting from becoming monotonous, and creates a standout visual effect without totally dominating the piece. Creating the emphasis means using different form or color from the rest of the piece so it stands out in a subtle way. Most artists place the center of interest off center in the piece so as not to draw all attention away from the other elements.
Balance can be symmetrical and completely evenly balanced, or asymmetrical and unevenly balanced. Not everything can be on one side of the piece, while the other side looks like a barren wasteland. For example, placing a large component in the middle of the piece means it needs to be balanced with a small piece placed toward the edge. Put balance in the piece by using color, form, movement and texture as well as objects as shapes.
Harmony or Unity
Achieve harmony or unity by ensuring that all the parts work together to form one satisfying effect. Nothing, not even the center of interest, should distract from the overall piece. Everything on the piece has a relation to all the other elements in some way. For example, if the composition of the piece has several flowers overlapping, placing a hammer into the image would destroy the harmony. A feeling of continuity on some level in each element of the piece creates more visual appeal.
Opposition or Contrast
Opposition in the artwork results from using a visual contrast of some type. Opposition forms when using opposing colors on the color wheel or when adding both horizontal and vertical elements to oppose one another. Using large and small elements or areas that include varying degrees of light and dark colors provides contrast and opposition. The contrast also gives it a feeling of depth.