How to be Smarter: Always dress up for a phone interview. It gets you in the right mindset more than anything else.
How to be Prettier: Hot liquids fill you up faster than solid food. Have soup and hot drinks to save calories.
How to be less Awkward: If you find yourself in a situation where everyone else is foreign, but you cannot hide your American identity, say you are an American raised in Luxembourg. No one knows where Luxembourg is, no one has a problem with Luxembourg, people respect Luxembourg. Go with it.