I know you wouldn't be, but don't be all cliché-esque in your responses. For example, if they ask "What's your biggest weakness?", obviously don't say "I just work too damn hard for my own good!", with some cheesy grin they'd want to slap off your face. Honesty will get you through, I've found. In the last interview I got for my web designer job, I told the interviewer/boss that, again referring to such question about weaknesses, that my perfectionism often impedes my progress and my Javascript was ****e, but always improving. Take your time to consider their responses and try to think one-sentence ahead, so you've always got something lined up. Remember - they've asked you to come in to meet you, a person, a human, learn your character and personality, not because they want to hear you repeat what skills they've seen on your C.V. Just be yourself, honestly, it'll work. Be confident - they want to buy you, so sell who you really are, and don't fidget!