Shizen (naturalness, absence of pretense) - Gardens (and arguably any aesthetic object) should be natural. Design with the intention of making your creation look as though it had grown that way by itself. If you have obviously man-made objects involved, do not try to disguise them. (ex. Cement mortar or brick looks better untouched than painted.) Choose simple objects which will fit in with the natural surroundings.
Odd Numbers - When placing elements in a composition, use odd numbers such as one, three, and five. This will better result in a sense of natural asymmetry.
The Triangle - Compositions such as groupings of stones, branches on a tree, etc. can be judged based on how easily one may draw an imaginary triangle between any three elements.
Fukinsei (asymmetry or dissymmetry) - Balanced symmetry, as humans devise it, does not exist often on nature. Therefore, it is better to make designs asymmetrical if one wishes to create an impression of naturalness.
Kanso (simplicity or brevity) - Less is more This idea is most evident in Zen gardens, where a single stone may encompass the idea of an entire mountain or island. Remove what is unnecessary, and the composition will be strengthened.
Yugen - Subtly profound, suggestion reather than revelation.
Datsuzoku - unworldliness, transcendence of conventional.
Seijaku - quiet, calm, silent.
Koko - (austerity, maturity, bare essentials, venerable, abstraction) - Water is a prime element of a garden, but raked gravel or carefully arranged flat river stones can create the impression of water.
Contrast - Contrast can be used to create tension between elements. Tension can create energy, motion and harmony.
Lines - Perpendicular lines create tranquillity. Diagonals create tension. Curves soften the effect.
Ma (space) - There is openness in everything and nothing exists alone. All objects interact with one another in space. In fact, the space of the garden only exists because there is a larger space outside of it. Where is the space in the composition? Why? How does the composition breathe?
Layers of time - Some parts of a composition change with the weather or the angle of the sun. Some change with the season. Others, like stone, hardly change at all for centuries. Yet time changes everything eventually. Good design considers this.
Meigakure - This is the quality of remaining hidden from ordinary view. All compositions have a best viewing angle. Find it or create it and control how the viewer approaches and is able to see the composition. For example, bonsai are, in essence, two-dimensional views designed to be viewed from the front only. Set your garden path so that only a single branch of the cherry tree can be seen around the corner and you guarantee the viewer will round that corner. Design the viewers experience, not just the garden. On the other hand, do not over-complicate.
Wabi and Sabi - Two of the hardest concepts of Japanese aesthetics to express in western language, generally they are wabi; subdued taste, austere, and sabi; rustic simplicity, mellowed. These terms were created by the Tea masters of the sixteenth century.
Shin, Gyo, So - Shin; controlled or shaped by man, So; things in their natural state, Gyo; the blending of Shin and So to compliment each other.