It should be noted that many of the design principles above are opposites:Context calls for considering exactly how a design will be used but flexibility calls for a design that is broadly useful in contexts that you may not be able to imagine. Minimalism calls for eliminating complexity for philosophical reasons while essential complexity supports making designs complex if there is some need for complexity.Ban the average calls for designs that are broadly useful for all people while audience calls for designs that are for an identified group such as a target market.
AlignmentPositioning things in a line.
HierarchyArranging things in a hierarchy of importance.
ContrastUsing visual contrast to create emphasis and draw interest.
Ban the AverageNot designing things for the mythical "average person."
Design to the EdgesDesign things to be usable for as many people as possible including people with disabilities.
Human ScaleDesigns are for humans and consider their characteristics such as how people perceive colors.
SpaceUse negative space to make designs less loud and chaotic.
Essential ComplexityOnly increase complexity where it adds value.
MinimalismThe philosophical as opposed to rational reduction of complexity.
FlexibilityDesigns are broadly usable in as many contexts as possible.
PersonalityCreate designs that have an identity or feel to them.
ContextDesigns consider context of use.
AudienceConsider user needs and perceptions.
More is DifferentComplexity can add value .. avoid needless minimalism.
UnityThe elements of a design are arranged such that they look like they belong together.
VarietyDesigns need not be homogeneous and can include elements that are distinctive and unique.
BalanceMake both sides of things appear to be in balance.
RepetitionElements can be repeated to create consistency and unity.
RhythmMultiple elements can be repeated in a pattern.
ProportionFind balance in the relative sizes of things.
ProximityGroup related things close together.
EmphasisDesign may draw attention to one element with techniques such as contrast.
MovementConsider how the user's attention flows through a design.
Genius LociDesign things to suit their time and place e.g. not copying historical styles.
Truth to MaterialsMaterials don't pretend to be something they're not. For example, a plastic phone that pretends to be gold.
Least AstonishmentThings work the way users expect unless there is a very good reason to change this.
Least EffortMake things easy for the user.
Input is ErrorThe aggressive minimization of human input whereby having to ask the user is viewed as a failure of automation.
ScaleDesign things to seamlessly scale up and down.
Keep it SimpleAll else being equal, a simple design beats a complex one.
You Ain't Gonna Need ItAvoid too many functions and features. e.g. obscure gestures that few people use but people might trigger by accident.
Worse is BetterAvoid excessive quality. Designs can be launched and improved over time with user feedback.
Last Responsible MomentAvoid making design assumptions or decisions too early -- let things evolve a little.
Defensive DesignBrainstorm the edge cases and worst cases and design for them.
Form Follows FunctionFunctionality drives design and not the other way around.
ModularityBreak things into parts that fit together
Interchangable PartsStandardize parts for efficiency.
There's More Than One Way To Do ITThere is no perfect design just many good designs.
LearnabilityIf you have to explain a design feature to the user, it might be too complex or obscure.
Information ScentProvide clues about how things work.
Attractiveness PrincipleAesthetics are personal .. there is no one design that everyone likes.
EmpathyGet to know the user and learn to feel what they feel to improve a design.
ConvivialityDesigns can feel friendly or unfriendly.
ExtensibilityDesigns adapt well to future change.
EleganceA design that feels simple, intuitive and appealing that is in fact extremely complex.