Diagrams are an essential part presentations and Nancy Duarte knows it. In her book Slide-ology she gathered many type of diagrams and organize them in a taxonomy. Now, Duarte Design has come with a great idea, Diagrammer, a collection of diagrams in a simpler taxonomy that presenters can buy as PowerPoint slides.
I recommend you check out them out. The basic taxonomy will just be enough to get you started using the right diagram for your task. I used the linear-flow diagram to represent a progress that otherwise would go in a list of bullet points: