Number 1 is to put the guest at ease. This can be done by simply smiling and greeting them in a soft voice.
Number 2 is to get them to like you. This can be done by simply saying something nice or funny that you can both agree on.
Number 3 is to get them to trust you. This builds up over the service by actually letting them know and acting expediently on their requests. For example if you have ordered an appetizer right away for them. When you return to take their main course order state that the appetizer has been ordered and should be out shortly. If you don’t say that they may think you forgot to order it.
I put these 3 right up there. Without them your tip will suffer and complaints will follow.