1) Take into consideration that you were most likely asked to speak because you have knowledge about the topic.
2) The most important thing --- don't panic. If you can, find a copy of the presentation handouts and scan them, writing down the main topics for each portion of the presentation.
3) This allows you to quickly look at the content of the presentation.
4) If the original speaker planned to use slides, quickly skim each slide and write down the key points.
5) Do not concern yourself with the exact words on the slide.
6) If the slides are properly prepared, each will have only a few key phrases --your talking points for each section of the presentation.
7) In the event you don't have a co-worker's handouts or slides, quickly develop an outline or mind map and do the following:--
a) List your main points and write down a few key words about each
b) Speak spontaneously and confidently from your heart.
c) Trust your experience and knowledge.
d) Focus on your message and not on the fact that you had to rush to put together a presentation
e) Present your main contributions right away.
f) It's extremely important that you emphasize your contribution and distinguish what you've done that adds to the literature.
g) You may want to repeat your list of contributions at the end of the talk, but don't try to keep the audience in suspense! Let them know your contribution immediately.
h) This helps the audience focus on how to assess your paper and means that even those in the audience who leave early will have a good idea of what you want them to take away from your talk.