Visibility of system status
The system should always keep users informed about what is going on, through appropriate feedback within reasonable time
Match between system and the real world
The system should speak the users' language, with words, phrases and concepts familiar to the user, rather than system-oriented terms. Follow real-world conventions, making information appear in a natural and logical order.
User control and freedom
Users often choose system functions by mistake and will need a clearly marked "emergency exit" to leave the unwanted state without having to go through an extended dialogue. Support undo and redo.
Consistency and standards
Users should not have to wonder whether different words, situations, or actions mean the same thing. Follow platform conventions.
Error prevention
Even better that good error messages is a carefule design which prevents a problem from occurring in the first place. Either eliminate error-prone conditions or check for them and present users with a confirmation option before they commit to the action.
Recognition rather than recall
Minimize the users's memory load by making objects, actions, and options visible. The user should not have to rememebr information from the one part of the dialogue to another. Instructions for use of the system should be visible or easily retrievable whenever appropriate.
Flexibility and efficiency of use
Accelerators -- unseen by the novice user -- may often speed up the interaction for the expert user such that the system can cater to both inexperienced and experienced users. Allow users to tailer frequent actions.
Aesthetic and minimalist design
Dialogues should not contain information which is irreleveant or rarely needed. Every extra unit of information in a dialogue competes with the relevant units of information and dimishes their relative visibility.