PPT is a powerful medium and businesses across the spectrum have benefitted from it. But its efficacy increases by a fair margin when you as a presenter compliment it with your speech at the start and end. You can even communicate to your target-audiences through e-mail or any other mode of communication in advance.
When you emphasize the main message of your PPT before its start, your audiences get ready at their subconscious-level to receive that. You get them mentally conditioned for the impending presentation. If you have communicated to them earlier at any stage about the gist of the presentation, they would be mentally prepared to receive the details. But whether your e-mail earlier or the speech just before the PPT-screening, you have to merely outline the summary of the PPT to trigger responsiveness in audiences. Even a small clue before the screening of the presentation goes a long way to help them understand its core idea in entirety.
These days everyone is active on one Social Media Channel or another. You can communicate to your target-audiences on these platforms about the theme of your PPT. You can make a build-up about your project, products or services mentioned in the PPT on these platforms which, according to you, are frequented by your prospective clients. You can present your vision and perspective about your new offerings in blogs. These blogs, beforehand, would make a base for your PPT. The key is to engage your target-audiences to your offerings before the actual screening of the PPT. You keep highlighting the problems and present the solutions in the PPT and this PPT will have a resounding impact.
After finishing the PPT, you must drive the audiences to ask related questions. And if they want time, they must be encouraged to ask questions through e-mails. You must provide them the information about your presence at different social media-channels so that they keep in touch and your chances of creating business remain intact.
Having them questioning at length after the event is perfect, but bear in mind that giving a complete picture in the starting speech or earlier communications diminishes the relevance of your PPT. So, give a tiny indication of the subject before the start of the PPT-screening and have an elaborative approach after its end.