Don't say you are a quiet/shy/nervous person. I promise you, you will not get the job. They need to know you are friendly and outgoing and you need to fake it to make it if you want good tips.
Just relax, lay off the caffeine. Smile a ton, be flirty if you have to, act very interested, compliment the food/decor, whatever. The food industry is a really kiss ass industry.
So, so you think you can tell Heaven from Hell,
blue skies from pain.
Can you tell a green field from a cold steel rail?
A smile from a veil?
Do you think you can tell?
And did they get you to trade your heroes for ghosts?
Hot ashes for trees?
Hot air for a cool breeze?
Cold comfort for change?
And did you exchange a walk on part in the war for a lead role in a cage?