There are so few “rules” in the world of art and design, which creates a lot of dissonance for many people. In math, there is only one right answer, but in design, there could be many, good options.
One of the few rules in design is the Rule of Three, which is the principle that holds that odd numbers offer highly visually pleasure. The Rule of Three is used in interior design as a way to group furniture and accessories. Odd numbers look dramatic together, as they create interesting, asymmetrical design.
There are many sets of three or five decorative accessories sold together in stores, such as candle stick holders, vases, floral arrangements and so much more. When grouping objects on your own, be sure to stagger the heights and vary the textures.