I applied online and received an invitation to an open house. I was the first to arrive and briefly chatted with the SkyWest flight attendants who were conducting the interview. Waited for others to arrive, chatted with them. Once it was 6:00 pm the flight attendants told us about SkyWest and the job. We were a small group, so afterward we took a small break and went straight into one on one interviews with all of us instead of the public speaking part. The setting felt very relaxed and informal because we were such a small group, which was nice. The flight attendants were kind and easy to talk to, and you can tell that they were passionate about their jobs and that they loved what they did. At the one on one interview they asked me several questions. Again, it was relaxed and they were so easy to talk to, so I didn't feel nervous.
My advice is be as confident and relaxed as you can. Be alert and attentive, but don't talk too much/try too hard. Don't try to dominate the conversation/room. Be poised and respectful of others. Some people get nervous and talk too much. Others get nervous and overthink everything they do or say. Relax, relax, relax. These are just people. They get nervous too. They got dressed up for an interview too.
The interviewers want you to succeed. If you know this is a the right job for you, trust that and trust yourself. Prepare your answers. Prepare your 60 second speech on why you want to be a flight attendant. Know why you want this and understand why you would be a good fit for the position. Smile, connect. Listen to the flight attendants talk about the job. Pay attention. When they ask you a question, reference things they said in their own speeches, if possible. I didn't plan to do that, but I connected with what one of them was saying so much, that in my one on one I referenced something she had said and I could tell she appreciated it. She knew I was paying attention and she knew I understood where she was coming from. But above all, relax relax relax, and be natural.