I freeze in interviews, tips? - any advice?

I have an interview on Thursday and my stomach is in knots. I want to come across as confident and honest. Any questions to ask at the end?

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

Thanks for writing this out. I went through something close to it 3 months ago, and it got easier once I kept a simple log of every call and form.