Make sure that you clearly understand the material and have thought through logical conclusions. Establish what you want to achieve by your presentation. Be sure you know the messages you want your audience to take away with them. One is to inform people about your product or service, and two is to then persuade them to buy it. You need to understand the purpose of your presentation in order to define its structure.
Group presentations are a good way of motivating an audience.
They are also the most effective for communicating broad concepts. This isn't the time for detailed discussion of nitty-gritty issues. It would be boring and a waste of time for most of your audience. T here are two parts to this question. I t isn't always obvious who should present.