What can I do to improve?

So how comes some people seem to click more easily with people than others? Is it something one can learn or does one have to be born with it? Do I have to be a people person to build rapport with people?

Fortunately, for me at least, rapport is a skill that one can learn! Rapport involves being able to get connected with other people and being on their wavelength. As much as 93% of the perception of your sincerity comes not from WHAT you say but HOW you say it and how you show an appreciation for the other person's thoughts and feelings.

When you first meet someone, you should always try to learn something about that person that you can relate to an experience in your own past. It's fun to talk to someone with whom you have something in common, an event, a mutual acquaintance, or some other shared history. You can always find something common with anyone if you try. This builds confidence. Confidence breeds respect, and respect builds trust.

Casual conversation, small talk or beating about the bush, does have its place so you shouldn't be too eager to jump directly into business or some other agenda. Of course, this should not be overdone.

It's important that you don't come to a meeting or negotiation with one agenda - your own! Rather, come with an open mind. You miss a valuable opportunity to build rapport if you are inflexible or don't listen. Being an active listener is often more important in building rapport than being an active speaker.

The wikipedia lists a number of techniques that are supposed to be beneficial in building rapport such as: matching your body language (i.e., posture, gesture, and so forth); maintaining eye contact; and matching breathing rhythm. Many of these techniques are also found in Neuro-Linguistic Programming (NLP).