Building rapport with the person we are talking to is something we often naturally do, however this is a skill that we can improve upon, once we become consciously aware of how to do this.
If you watch two people deep in conversation, you will notice how, after a while, they begin to shift their position, breathing, voice tonality or speed, to match the person they're talking to.
This is because we send out unconscious signals in order to gain the other's approval. Everybody wants to be liked, no matter if they tell you otherwise. Some people are so bad at getting others to like them that they develop a 'couldn't care less' attitude as a defense mechanism - but deep inside they still care. These people clearly lack communication skills, even if they appear on the outside to successfully interact with others.
To an outsider, such a person may appear confident and self assured - but on the inside both they and their audience know that they're putting on an appearance because it's easier than being confrontational.
People like People who are like Themselves
We are all drawn towards those who are like ourselves in some way, which is why so many people join clubs or other organizations to in order to meet others with similar interests.
If you wish to improve your communication skills then you will need to discover what you have in common with someone in order to share your ideas and possibly form a lasting friendship.
To reach this stage you will need to engage people in conversation by building up a rapport. This could start with a simple smile and acknowledgement of the other person's presence, leading on to small talk with those you don't yet know.