The method selected should be based on the type of insights you're trying to gather. For example, if it's behavioral data you might start with an empathy mapping with stakeholders so that when you conduct customer interviews you can validate your assumptions, identify where there are gaps, and highlight new and actionable insights. That all being said here are a few other methods I like.
- One to one interviews
- Sitting in on sales and customer support calls
- CX Moment and outcomes map is a great method for know where and when to introduce the voice of the customer surveys, analytics to prompt customer success team engagement, etc.