Script your words wisely
Something I've found that helps prepare me for interviews is writing down, beforehand, what it is that I want to say.
If I have a basic script to follow for the top ten (or twenty) questions, then if I'm asked anything from, "why should we hire you?" to "what do you think about x?" it's a lot easier to remember and to weave a cohesive narritive.
Furthermore, if you keep your quips short and focus on delivering something engaging, quality not quantity so to speak, you'll up your chances of making an impactful impression from the start.
That's the point isn't it?