20 usability guidelines by Susan Weinschenk and Dean Barker.
The interface will allow the user to perceive that they are in control and will allow appropriate control.
The interface will not overload the user's cognitive, visual, auditory, tactile, or motor limits.
The interface will fit individual tasks within whatever modality is being used: auditory, visual, or motor/kinesthetic.
The interface will fit the way each user group works and thinks.
The interface will communicate as efficiently as possible.
The interface will have a tractive and appropriate design.
The interface will present elements simply.
The interface will behave in a manner such that user can accurately predict what will happen next.
The interface will make reasonable guesses about what the user is trying to do.
The interface will be free from errors.
The interface will have the highest possible fidelity.
The interface will allow the user to adjust the design for custom use.
The interface will provide a satisfying user experience.
The interface will match the user's social customs and expectations.
The interface will operate at a tempo suitable to the user.
The interface will be consistent.
The interface will provide additional assistance as needed or requested.
The interface will allow the users to perform a task exactly.
The interface will make actions recoverable.
The interface will inform users about the results of their actions and the interface's status.