Working your audience

Converse
Have a conversation with your audience. They may not actually say anything, but make them feel consulted, questioned, challenged, argued with; then they will stay awake and attentive. Your job as a presenter is to stimulate and communicate with your audience into wanting to get the information you have, not just to present that information at them.
Interact
Engage with your present audience, not the one you have prepared for. Look for reactions to your ideas and respond to their signals. If the light bulbs are not going on find another way to say it. Monitor their reactions; it's the only way you'll know how you're doing and what you should do next. If you don't interact you might as well send a video recording of your presentation. It's why you came.
Show conviction
Give an expressive presentation and an enthusiastic presentation and your audience will respond, which is what you want. At the very bottom line disagreement is preferable to being ignored. Use your excitement, pace yourself to give an exciting presentation, use something you know you feel strongly about to build up to an important point or as a springboard to another idea.
Get some perspective
The odds are that someone in the audience will not like you or may disagree with you. There will probably be someone else out there for whom you can do no wrong. As a rule of thumb, the majority of most audiences want to like you and what you have to say - they want you to be good. They didn't come hoping to be bored or irritated by your presentation.