I freeze in interviews, tips? - any advice?

I get tongue-tied when I am asked about my weaknesses. There are 16 people counting on me, so I am trying to be careful. I want to come across as confident and honest. Any questions to ask at the end?

Arrive early, drink water and take a slow breath before you walk in. It sounds simple but it helps.

Prepare three stories with a clear beginning, action and result, and adapt them to the questions.