In the course of User Interview, Usability Test, Concept Test, Field Research, or Exploratory Research, you will be interacting with participants first hand. You need to capture the raw data that will be used throughout the rest of the research process.
There are multiple needs competing in how you capture data: (1) create a record you can refer back to for verifying your understanding, (2) maintain a traceable record of source data that will back up your derived user insights, (3) have the appropriate evidence on hand (audio clips? photographs? verbatim quotes?) to deliver compelling insights / reports, (4) treat your participants ethically and minimize the data you record about them.
Consider that all data you collect has a "weight" you will have to deal with down the road. The more you capture, the more you have to process. And the more personal information you record about your participants, the more care is required for consent and storage. The simplest form of recording data is taking notes on the spot. Increasing in weight are still photographs, taken with participant consent and subject to participant review. Heavier still are audio recordings of the interview (which imply a need for transcription), and then video recordings of the interview (which imply a need for review, editing, and production.)
Therefore, always identify ahead of time the "least viable data" you need to capture, and be prepared to do so. Ensure you have the right equipment to capture that data, fully charged, with battery backup, and redundant options available in case of failure. Make it a standard operation to secure that data in the project's home structure whenever you have completed your interview. The guidelines for capturing raw data should be followed by all researchers across all projects, with periodic reviews to match operational practices with the development of your team’s research practice.
It is crucial to have a well structured system in which you will Manage / organize raw data. Rigor in capture and organization allows you to simply and efficiently review your findings as you conduct Session debriefs, run Affinity mapping workshops, and move into more Open-ended qualitative data analysis...