"Always aim at complete harmony of thought and word and deed." (Mahatma Gandhi). To this wise adage if I may add, aiming harmony in design is crucial; I do not think I will be too far off.
Harmony pulls the pieces of visual elements together. It drives at achieving visual rythm in trade shows notoriously known for clutter and chaos. Adjacent colors, related textures, similar shapes and of course the golden ratio are the principal attributes in fostering balance and congruity. Start with a limited color palette. Use tonal contrast as the key element to emphasize focal point. You might want to play with formal balance or an informal balance for the overall movement.
If the sentiment of your brand is dignified, restraint and conservative you might want to go with formal balance. Elements on the right side of your display mirrors the left side in size, placement, shape, and color. Usually banks and retail sector might go with this kind of a structured layout.
If the brand is conceived as exciting and playful, informal balance is the way to go. There is imagination, randomness and discovery at play here. If you wish to promote activity, excitement, and variety use informal balance but nevertheless there needs to be some kind of connective tissue that unifies your exhibiting space.
Harmony in your booth design is bound to amplify the voice of your brand. If some contrast is weaved in this spatial harmony it makes the brand exciting and memorable. Understatement is always better. Sometimes a tiny bit of contrast is all that you need. Be it flooring, lighting or perhaps interjecting some curvacious furniture is all that you need.
The principles of harmony and contrast may seem completely contradictory, but it is the fine balance between these two that dictates the dominance of brand.