Four things people do to mess up their interviews, regardless of degree obtained.

1. Show too much humility.
If your group's project was successful, and assuming you at least showed up and did what was expected of you, I sure hope whatever you did was important to the project. I'd much rather hear about how important your part was than how you managed to get your socks matched every morning.

2. Show too little humility.
Behind every great leader is a great team. A great leader strives to leverage the strengths of each team member. Talk about this, not about how you managed to squish their hopes and dreams in one short quarter.

3. Be passionate about nothing.
Everybody else in the room has a pulse. I've never met you before, so I don't know what makes yours stand out.

4. Be passionate about one thing and one thing only.
Surely you are a person of many talents. Whatever will you do if we decide to do something else? Burn down the building? (No, wait, Milton did that.)