We had been socializing the idea of employment for a month or so, so the actual job interview was a bit of a formality. My reputation from previous employment was really the key.
For a few weeks we talked on the phone. When I finally got serious and we set a date for the interview in person, I was surprised to find out how relaxed the members of the interview panel were. It was a long day, but not really stressful since I had an offer letter already as well as a couple of companies with interest.
The final offer for the job and salary negotiations was over dinner with the head guy. He offer the salary and finally provided a job description (it was a little loose up to that point). I countered on the spot with the offer letter I already had and he accepted my counter.