How we change what others think, feel, believe and do
Interest in the person
A simple way of showing interest in the person is just by using their name.
After initial interest, pause to determine what effect you are having and if they are not looking happy with your interest in them, then back off (itself a technique that may lead to them then following you).
Look for points of connection from what they say. Show that you are similar to them.
So what did you get up to at the weekend, Sam?
Where are you from? ... Oh, my cousin lives there...
Which train do you catch? What do you think of the service?
I am the most interesting person I know, and when others seem to agree with this, I will happily go on about myself and my opinions as long as I have an attentive audience. Showing interest in other people can thus be an easy way of extending the conversation.
This also gives you lots of information about them that can be useful. Showing similarity, for example, increases bonding.
A caveat: Too much interest in a person may be taken as an undesirable advance or even leading toward harassment. Be careful that your questions are not considered intrusive.