From De Anza College International Student Handbook on the topic
Dating:
When you first start interacting with Americans, it might seem a little awkward in the way they joke around and socialize. Someone you meet may find an interest in you, or you may find an interest in him or her. So if you are interested, how do you make the first move, and if you're not interested how do you tell that person?
If you like them: Tell them that you find them interesting and ask them if they would like to have dinner or coffee sometime. It is all right to be direct in these cases. Don't worry, even most Americans find this difficult.
If you don't like them: When they ask to see you sometime, simply tell them "Probably not, but thank you."
If you want to stop seeing someone or if you are not interested in having sex with someone who is pressuring you: Tell them directly what you want. Don't be afraid to state your mind or else they may assume you are still interested.
Gosh I love this country!