Know about the company, read case studies about how they work with different customers as it does vary quite a bit.

I went through 2 rounds of in person interviews after a brief phone interview. Everyone was exceptionally friendly and accommodating of my schedule. The focus on their #1 core value, "We will be the easiest company you have ever worked with, whether you are an employee, customer or investor" was already showing. The interview questions were relevant, purposeful, and on target. There were no "trick questions". They were candid and to the point, and as long as you are comfortable with the idea of speaking truthfully, they were not intimidating. They showed me that they care about getting to know each and every employee by having me interview both with my direct manager to be and with senior management. They asked me about what I like to do, including "do you see yourself as a hunter or a farmer?" which is something every sales person should know the answer to. Overall, it was a comfortable process, and the timing worked perfectly for me. It was a 2-3 week process, but that had to do with both my personal schedule and that one of the hiring managers was out at trade show.