Be a good listener.

When I was a young man: a good friend of mine, who was a bit of a Romeo, gave me sound advice about how to interact with members of the opposite sex.  He said, be interested.  Ask lots of questions and listen to what you are being told.  People love talking about themselves, and at the end of the conversation, if you have listened, the other person will feel great.
 This advice holds true when you talk to anyone.  Maintain eye contact, with soft eyes, to show the person that you are listening and interested.  You never know, you might learn something.