Rapport is the process of making an unconscious connection with your subject.
Methods of building rapport are often taught in books about business and dating -- here we will stick to it's use in hypnosis, though you will find the techniques learned applicable to many aspects of your life.
Whole Body Matching - Whole body matching is where you conform your body to a similar stance and posture of the subject. This does not mean to exactly mimic. It means is to have your posture and stance similar. For example, if you're subject has their legs crossed at the ankle, you can cross your legs at the knee.
If your subject changes their position, you can modify your position. But abstain from making choppy abnormal movements when shifting your body to match. Move in the most natural way possible.
Cross Matching - Cross matching is where you can match the subject's stance or gestures by doing them with the opposite part of your body. For example if the subject folds their arms, you could cross your legs. If they are shaking their feet you could tap your fingers.
Gestures - Everyone has gestures that they use frequently. Examples: moving hands while speaking, touching our face frequently, etc.. Take the time to detect the subjects gestures and work them into your own natural gestures.
Breathing - Breathing is probably the simplest way to create unconscious rapport. Begin by mimicking the pace at which the subject is breathing. After a few minutes, take a deep breath...then change to your natural breathing pattern. You will notice that quite often, the subject will now be following your breathing pattern.
Vocal Matching - This requires matching and pacing the features of the subjects voice and speaking pattersn. There are several qualities you will want to match in order to obtain rapport. Tone, intensity, pace, and volume are some of the most obvious qualities. When matching a subject's tone of voice, adjust your voice slightly towards his or her tone.
One of the details you will notice when talking to a subject is that their particular words or phrases they repeat. They use the same words and phrases in many different contexts. By noticing these words and phrases then using them in your communication with the subject, you'll be able to obtain a deep rapport.
Most people use one dominant modality to articulate themselves in communication. The three basic modalities are visual, auditory and kinesthetic (feeling). To gain rapport, a hypnotist will mirror the subjects use of modalities.
You can easily discover what modality your subject uses most just by listening to them and finding the kinds of words they use:
Visual: Everything looks so clear to me. I see what you are saying.
Auditory: That scheme has a nice sound to it. I hear what you are saying.
Kinesthetic: You feel like a warm caring person. I understand how you feel.
Once you have discovered your subjects main modality, you can adjust your speach to use the same.