I build long-term relations with clients by getting to know them not just on a professional level, but a personal level. As individuals, we have likes, dislikes, and various hobbies. So with that being said, I would attempt to find the common ground between our likes and hobbies and really focus on that to get to know them. If you get someone talking about things that they like, they tend to give you additional cues to continue building that long-term relationship. I would use this to build rapport on the common ground that we could agree on and stay away from anything we may disagree on. By doing this, it shows that I care about them and not just trying to sell them on something.