Well said ladyinred. To add to her list of things not to do to look stupid or out of place, do not wear sweat-pants or sweat-shirts, more so with your college/university mascot or US flag, or shorts to restaurants. It just looks trashy in the european environment. If you lack a good sense of fashion style, look around and try to pick some from the people there. And when in France, try their smoked salmon sandwich. It is delicious. And expect most public places in France to smell of cigratte smoke as almost everyone seems to smoke there. If visiting Eiffel Tower, plan to spend at least few good hours there and do so in the evening so that you can enjoy the picturesque tower when it starts to get dark with it's golden lights.