There's two ways to go about it depending on your situation. First is to be open and honest as it's the best way to get people to open up and actually start a conversation. The second is to keep to yourself and keep people at a distance because you don't want to be bothered. There's no point in bullshitting and being ashamed of where you're from. Unless you're from Boston.It depends on where you go. I imagine if you're a first time traveler you're going to somewhere where they love American money.
Edit: What Dyvim said.