Consider where you place each element of the garden based on the following:
The aspect is which direction the feature faces or its position in relation to, for example, a house. Examples (in the northern hemisphere):
It is usually cheaper and easier to build hard landscaping structures on level ground than on slopes. If designing for a slope, then the engineering of the structure must ensure that it doesn’t fall or slide down the hill. Often, if building on a slope, level areas for foundations must be dug into the slope which means a large amount of earth movement, which can be expensive, and retaining walls may need to be built on the downhill side.
If features are too close together then they can interfere with each other. The pond and plant pot in this picture block the end of the path making it too narrow. Conversely, if features are widely spread around a garden they can look as if they are disjoined or scattered and not part of a single cohesive design.