One of the easiest things to do to get a good reaction from the audience is to schmooze with them before the presentation. I actually start this by pre-program phone interviews before I even get to the state where I'm speaking. This tip has to do with schmoozing right before you go on stage.
Whenever possible make it a firm point to have your presentation equipment and materials set up and tested long before anyone is expected to arrive at the meeting. When the attendees do begin to arrive, start introducing yourself as the speaker and shaking hands with them. If they are coming in a few at a time, you should be able to spend a few minutes talking to each group. Either make small talk or ask them what they want to get out of being there. Pay particular attention to people that are bythemselves and facilitate introducing them around if it's appropriate . . . at any rate, make them feel at home.
These small gestures will create tons of rapport and cause most of the people that you've touched to be rooting for you.