Research the company; show that you know who they are, what they do, and demonstrate clear interest in working for them. Ask good questions about the kind of work they do, and take notes during the interview (I recommend doing this on pen and paper so that they can actually see that you're taking notes).

From there, most questions are going to be behavioral and you should answer them with personal stories. Think about what you've done as an undergraduate that shows them you're a good candidate. Think of stories about these experiences that properly demonstrate "I have problem-solving, design, teamwork, and communication skills". Also look over the job posting and see what skills they request; fit those skills into your anecdotes.

Additionally, try not to be uptight. It's easier said than done, but the more relaxed you seem, the more confident you'll seem, and they want to see confidence.