Speaking to users at the problem definition stage, gaining first hand experience and testing initial assumptions.
Surveying users to gain top-level understanding of their expectations and needs, typically resulting in more in-depth discussions. Protoyping (from determining everything needed to be tested to designing prototypes themselves) and testing with users.
Designing usability testing on live software which includes mapping a set of test goals and designing the tasks around those. It may also include designing training material for testers outside the team.
Documenting, analyzing and sharing testing results. I typically capture as much data as possible, and create formats that others can consume. Testing data is useful