I use personas as a touchpoint and reference for the needs of the users I am designing for.

Procedural task analysis provides a visual layout of the flow of a task and a user's choices. This helps account for all possibilities in a design. Here is an example of a procedural task analysis for installation of an IoT system.

Hierarchal task analysis breaks tasks down to find pain points.

Usability testing is essential to discovering pain points for a design.

Use cases are effective for communicating exactly how a product should behave.