Use visuals when presenting. People recall 20% of what they hear, 30% of what they see and 50% of what they see AND hear. The percentages go up even higher when you add touch. So if, in a presentation, you can get your client or prospect to see, hear AND touch (or be interactive in some way), you will go a long way to improving your presentation, improving your relationship, and getting them to favorably remember you long term.
I once attended a seminar where there were about 500 attendees. The audience was asked to raise their hand if they learn best by hearing. A few hands went up. Then they were asked how many learn best by seeing. Most of the hands in the room went up.
We've all grown up in school having to take notes. That's one aspect of the "touch" part of learning, albeit a weak version of it. But it does demonstrate that retention improves when you incorporate several senses working together.
All this goes to say how important having a great portfolio becomes, filled with visuals to support what you're saying. But see if you can involve your prospect or client in some active participation to deepen the experience and it should have a positive effect beyond what you're now experiencing.