I freeze in interviews, tips?

I have an interview on Monday and my stomach is in knots. I have read a lot of threads here and could not find my exact situation. I have practised answers but they sound stiff. How do you prepare answers?

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

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