Americans rarely save face. It is viewed negatively when someone passes blame from a problem to someone else or makes excuses.
Americans are not good at “hints”, body language, or metaphors. They will say what they believe and believe what they say.
Americans can also seem "flaky," i.e.: do not follow through with social plans. If you make plans with an American, be ready for the possibility that the plans will change or be cancelled.
It is not uncommon for Americans to smile at someone while crossing the road, joke with another person in line, or talk to someone at an event without knowing this person, getting to know them, or even intending to get to know them.
Americans love “small talk,” i.e.: conversations without real substance such as weather, traffic, or uncontroversial topics in which everyone can find common ground.
The U.S. has a very individualistic culture. People are taught at a young age to do things on their own and a high value is placed on the “self-made” person, who rose from nothing to riches.
Equality is VERY important to Americans – even if in practice, it does not always happen. There are many rules in the U.S. (like waiting for a traffic light to turn green and waiting in line) that are very important. Americans also tend to become upset when others break the rules. Do not ever cut in front of someone in a line, or you may be yelled at.
Freedom is one of the building blocks of American culture. Americans believe that everyone has the right to say or think what they want, even if they do not agree with it.
This is a very regional preference. In many areas, is perfectly acceptable to go to class in your pajamas, whereas in other regions people may dress up to go to Walmart.
Americans normally take grooming and hygiene seriously, and it is not uncommon for them to shower 2 or 3 times a day, especially in the summer months. They may avoid you or make comments if you do not pay attention to or have a lapse in your hygiene.
Be polite when asking for something. Americans do not take well to demands. When sending an email or asking for a favor, show you are appreciative and do not just demand for something to be done even if you are waiting for something urgently.