Artists can unify their work in several ways as unity is the appearance or condition of oneness. which means all the elements in the work belong together to make up a coherent and harmonious whole. In the painting above by "Fra Angelico" called "The Anunciation". you can see how the work is unified thru similar patterns of shapes to give you a sense of variety and the balance between heavy and cool colors give you a feeling of diversity. to make all the elements in this piece belong together as a whole.

Asymmetrical balance in a painting means the left and right side are not the same balance. so in order to give you a symmetrical feel various elements are balanced according to their visual weights and forms. large forms are heavy and more attention getting then small forms. therefore a large form can be balanced by 2 small forms. Also colors, as warm colors appear heavier then cool colors.  in the painting above by "Johannes Vermeer", you can see the use of a symmetrical balance by the way the artist incorporated large areas of shadow with small areas of light. Also the woman used as the focal point in almost the middle of the painting is then counter balanced by large the plan empty area to the left side of the drawing for balance. The blue colors on both sides and the hints of yellow on the window curtain and to the far right as the painting edges creates that whole balance in asymmetrical work.

Scale also changes the meaning of artwork in various ways one of the ways is the illusion of depth or amplified perspective. This is done by contrast of scale. Contrast of scale is to change the size of an image or to create a surreal feeling to amplify ones perspective. in the painting above you can see how the artist used contrast of scale to give you this amplified perspective of the human body body in a sort of humorous way.