Generally, Americans like to laugh, and they enjoy being with people who have a sense of humor.
They usually maintain regular eye contract and smile a lot.
People often compliment each other, for example about their clothing or achievements, especially as a way to start a conversation – even with a stranger.
Americans also often ask, “What do you do?” to begin a conversation, and it’s very acceptable to ask about work related matters.
Sports are very popular in the US, especially baseball, football (American football, not soccer), and basketball.
Books, food, music, and movies are good topics, but not religion, politics, or other controversial subjects such as racism, unless you know the person you’re talking to well.
Finally, Americans will expect you to speak English as many never learn a foreign language.