Elements of the design interlock, overlap, or otherwise hang together.
The number of elements is limited by restraint and good taste.
All parts of the design are in pleasing relative proportion.
There is one focal point, or center of interest.
Pruning a dish garden to keep elements in size and proportion
If the design has formal balance, the focal point is in the center, with elements of equal weight at the sides.
For informal balance, the focal point is off-center, with heavier elements to balance it.
A design becomes fluid, rhythmic, with the dynamic use of line, and with pleasing contrast of colors, textures, and structural forms.