In the Tell ';n'; Show method of creating effective presentations, you tell you point, then you show it. So, each point requires some validation, some evidence. Which validation you choose may depend on your audience. Some people want hard data, others want to know what the competition is doing, and still others may want the advice of an expert. A story that conveys a poignant situation may be effective. Sometimes, all you need is an image to show what you';re telling. If you say that the copier you sell fits on a small table, a photograph will suffice.
After deciding on the points you want to make in your upcoming presentation, you need to figure out how to support those points. For example, if your point is that your company has the largest market share in the industry, quote the research (hopefully done by a third party) that says so. This applies to both business presentations and educational presentations. The support you provide for your message is essential for an effective presentation.