The student population at a US university can be extremely diverse, more so at the larger universities. If you approach this with an open mind, you can broaden your horizons! It is considered inappropriate to refer to a person's race, color, gender or sexual orientation in any way that is mocking or inoffensive. So, it would be a good idea to read up in etiquette e.g. about dining and conversation. As a thumb rule, it is prudent to respect a person's privacy and not ask too many probing questions about anyone's personal life.
Some people may think that the US is very liberal when it comes to interaction between men and women. While this is true as compared to many countries, it does not mean that people don't respect each other's boundaries. Dating can be fun, but do not throw caution to the winds. Remember, you are here to study!
You may find yourself in a social circle where drinking is a part of the Friday night culture. Always drink responsibly!