Published 21 Nov 2013
These are the overarching Meta Principles for Visual Usability as outlined in the excellent book Visual Usability by Tania Schlatter and Deborah A. Levinson. They marry principles for graphic design with principles for usability in a really great way.
You should definitely read the book for an in-depth explanation of how to apply these principles in your work.
Source: Visual Usability
Consistency is about making things look and behave the same to take advantage of user familiarity and expectations. You achieve that by establishing patterns within your app and use them consistently to crate visual language.
Hierarchy is about indicating differences that help people know how the app works, what's important, and what to do. Use the Gestalt Principles to establish a visual hierarchy.
Just as people react to other people, people react to applications. First impressions happen automatically, consciously and unconsciously. Other impressions are the result of interactions over time. Personality refers to impressions formed based on appearance and behavior, a concept that applies to applications as well as people.