Dieter Ram's 10 Principles for Good Design

• Good design is innovative.
• Good design makes a product useful.
• Good design is aesthetic.
• Good design helps us to understand a product.
• Good design is unobtrusive.
• Good design is honest.
• Good design is durable.
• Good design is consequent to the last detail.
• Good design is concerned with the environment.
• Good design is as little design as possible.

From the article: 1960s Braun Products Hold the Secrets to Apple's Future