Our presentation deck tends to be compact and to the point. Rather than big design words, jargons business people hardly understand, keep it simple with keywords and highlights. It also helps to include mockups on how the client visualize the design usages in different context. (i.e if we design a logo, show how the logo would look on a webpage, an envelope, or a t-shirt)
On the other hand, we focus more on the way to talk and pitch. Since we're not keen on formal presentations in which everyone's on guard, we try to make it into an open discussion. The point is to deliver our design process; show the client our works, explain how we get there and how every design decision we make links back to their requirements and business benefits.
Welcome their feedbacks genuinely. It's a perspective to keep us from being biased and falling in love with our ideas. But don't make any decisions on the spot, we all need time to digest and consider ideas opposite from ours.