What techniques do you use to elicit requirements, and how do you choose between them?

Match the technique to what you are missing. Interviews give depth and reveal the politics, workshops build shared agreement across teams, observation shows how work is really done rather than how people describe it, document analysis surfaces rules already written down, and prototypes unlock anything people cannot picture. Most projects need three or four, because no single technique gives you a complete picture.

I pick based on what I think is missing rather than what I am comfortable with. Interviews first usually, because they give you depth and they tell you where the politics are. Workshops when I need people from different teams to agree on something in the same room, because agreeing separately never survives. But the technique that has saved me most often is sitting and watching people work. On a claims project every person I interviewed described a clean four step process, and when I sat with them for a morning there were two extra steps involving a shared spreadsheet that nobody mentioned because it was not officially part of the process. That spreadsheet held a business rule nobody had written down anywhere. I also read whatever documentation exists first, so I am not spending expensive stakeholder time on things already recorded, and I use rough prototypes for anything people cannot picture from a description.