One of the greatest challenges that a presenter faces is feeling comfortable ceding control to the audience. After all, it's typical to invest hours building the perfect slide deck only to find that the audience wants to take the conversation in a different direction. When this happens, it can be frustrating. Perhaps you feel like you wasted time preparing materials (you didn't, people will still read your materials) or that the audience doesn't appreciate your knowledge about the subject (they do, otherwise they wouldn't be meeting with you).
When you feel this way, take a step back and ask yourself - why are we having this meeting in the first place? Generally the purpose of a meeting is to make a decision, so if you are the presenter, you likely hold some piece of information (data, expertise, etc) that are critical to the audience's ability to make a decision. Now transpose yourself to the viewpoint of the audience, why are you in this meeting? Generalizing again, members of the audience usually have some knowledge about the subject at hand but are looking for additional information from the presenter to make a decision. The nuance is that the audience is often looking for specific pieces of information - financials, features, competition, etc - but often before the meeting, the presenter doesn't know which topics will tip the decision scale. So how do you solve this puzzle other than trying to cover everything in a well prepared monologue?
Simple. Ask the audience what they want to know.
As the presenter, you hold the key, you have the information they need (as well as the information they don't). Trying being direct and asking the question: "What can I tell about X to help you make your decision?".
Completely giving up control of the meeting might feel awkward at first, but the benefits are clear: important topics are discussed first, unimportant details are left out of the presentation, and the presenter looks like a true expert - a person who can field any question[ . Furthermore, the candor and directness of the meeting will save time, something your audience will appreciate and attribute to your management skills, and make your audience feel more satisfied because their personal concerns were directly addressed.
Of course, not every meeting lends itself to this strategy (group training, for example, might be more of a one-way broadcast of information), but when there are decisions to be made, using questions and conversation to get to the points that matter most can be a winning strategy for both the presenter and the audience.