Interview nerves, what actually helps? (Oklahoma City)

I get tongue-tied when I am asked about my weaknesses. This is my first time dealing with any of this. I have practised answers but they sound stiff. How do you prepare answers?

I record myself on my phone and listen back. The second try is always better than the first.

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