Bill Westbrook, former CD at Fallon once said, "The difference between good agencies and great agencies is that great agencies sell their best work."
I've seen it happen over and over again, great ideas killed by bad presentations. Either the team thinks their idea is so great that the client will fall all over themselves once its brilliance is revealed. Or they try to bore the client into buying the work by droning on and on over every insignificant detail. So how do you sell an idea when even if a client's physically in the room he may not be mentally because he's checking his email or updating his facebook status on his iPhone?
First, have a point of view and limit the number of ideas you bring into the meeting. Get to the point. No straw dogs to make your favorite idea look better. If you bring it into the room there's a chance a client will buy it. That's a mistake I'll never make again.
Second, if the meeting is in person create a little theater to dramatize your idea. To kick off the meeting for a mobile phone client we held a funeral for the land line complete with flowers, candles and a eulogy. For another, we converted a conference room to a college dorm room to bring the target to life in front of our client's eyes. The theater must be strategic and relevant to the idea being sold. Done well, it intrigues the client and brings the challenge or opportunity of the assignment to life.
Third, engage the client throughout the presentation. The person talking is the person being sold. Ask them direct questions and phrase them in a way that will elicit an answer that leads to your solution. For a home security client we asked, "What things, other than guns, do people keep in their homes to protect themselves from burglars?" When the client answered, "a dog" the ad was sold, because when I turned the board over showing a cute, lovable dog it was now the client's idea as well as ours.
Fourth, if you're using PowerPoint, use it as a presentation aid, not the presentation. You deliver the information, the slide reinforces it. Make one point per slide, ideally with a headline and visual representing the idea. If you must use words other than the headline, keep it brief. No bullet points. No paragraphs. If you have to say, "sorry this slide is such an eye chart" then change it. You're not selling the client. You're annoying them.
Finally, rehearse, individually and as a team. Work on your transitions, your set ups, your closings. Anticipate questions and objections and if you don't know the answer, don't fake it. Write it down and get back to them.
Great presentations are not about being slick, they're about being persuasive and that happens when you're honest, genuine and prepared. I've seen too many great ideas die before their time. Hopefully this will help save one or two.