+1 on Joseph's answer. It usually pretty easy to answer technical questions in one's area of expertise, but self-critiquing questions are a lot harder. Assume you'll be asked some and pre-plan the basics of an answer.

Also, listen attentively to the interviewer. Don't interrupt and don't start framing your answers in your mind until the person finishes their question otherwise you might miss something.

Good luck, we are all behind you!

-Blast