There are several best practices that you can follow in order to improve the user interface of your product. Knowing your users is the foundation for everything, including understanding their goals, skills, preferences, and inclinations.
Unity is a measure of how well each element of your design works together. It describes the overall design and whether or not its components function in unison to express a single idea. Unity is the most essential Design Principle since it pulls your design together as a single cohesive unit.
The concept of similarity essentially states that when things share a visual trait, it is presumed that they are connected in some way. To be viewed as part of the same group, the things do not need to be identical, but merely share at least one observable feature like color, shape, or size.
Compare any two design elements. Either the elements are equal in every sense, or one has some amount of dominance over the other. The more dominant element will draw attention and be recognized first. It may even appear to have some control over the less dominating element.
The dominating element is likely to have more visual weight than the elements that it dominates. It will appear to exert force on everything around it.
Dominance in your design generates a visual hierarchy. By definition, a hierarchy is a succession of distinct levels of dominance.