Contextual Inquiry
Observing people in their own environment performing their actual work with your product.

Guidelines and Standards
A collection of guidelines and standards for the most common platforms.

Scenario-based Design (also called Task-Centered Design)
An iterative approach to system design that relies on stories of user interaction as the source of guidance for design requirements.

Usability Testing
Empirical (observational) testing of a design with representative users.

User Profiles
A summary of relevant user characteristics.