can anyone tell me the secret to charm?

princes aside, a charming person is most often not a lonely person. A charming person does not have to be good-looking or super-outgoing to attract people to them. 

What makes a person charming? Can anyone tell me how to be charming?

I believe charm is the ability to convince people are you a likable person, one of the best way to charm people is to make them feel acknowledged and liked. if you can make someone feel genuinely acknowledge and liked in a friendly way then they will feel great, because everyone is looking for validation that they are OK, that they fit in and are a good person. People want to be listened to and if you can bring them those for which they seek in a way that doesn't expose their wanting to receive it - because no one likes to admit they want those validations otherwise they will look weak and it hurts their ego - if you can do that then they will like you and want to talk to you more.

one way i find that people like talking to me is when i ask about what they like to do, then i like to ask more about why they like it and go into details of whatever it is they like. I get genuinely interest because i have the "i want to learn" attitude and so when i ask them they can see i'm actually interested and want to know more and they like talking to me because they get to talk about a topic they really like.

hope that helps