Presentation is one of the important skills which a researcher should have and a graduate student should keep learning and practicing. Presentations are often made for discussing research ideas or results on research meetings or conferences. A good presentation certainly helps much to delivering the ideas to the audience.
Scientific presentations have some differences with other kinds of presentations, sharing some common rules. I find a very good lecture from iBioSeminars by Dr. Susan McConnell. Dr. McConnel gives helpful advice on preparing and presenting an effective scientific talk and presentation including choosing fonts, colors and slide styles, ways to structure the talk and more.
The lecture: Designing effective scientific presentations. It is also available on Youtube.
The website also provides the Slides and MP4 format video and more to download.