1 tip on control
Make people quiet at your presentation
If people are talking while you are holding your presentation - you should make them quiet, because they are making both you and the rest of the audience distracted. But don't be rude - the last thing your audience wants is to see their presented gets upset on someone in the crowd.
The way to do it is by asking the talkers if they have any question you can help them with. This should usually do the trick.