Interview nerves, what actually helps? - what worked for you?

I get tongue-tied when I am asked about my weaknesses. I have read a lot of threads here and could not find my exact situation. I want to come across as confident and honest. How do you prepare answers?

Thanks for writing this out. I went through something close to it 2 months ago, and it settled down once I kept a simple log of every call and form.

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