Practice presenting your report at least once before presenting it in class. Time your talk so you know exactly how much material you can fit in, and how to pace the material. Don't just read your notes to yourself--stand up and give the talk the way you will to the class. You will find it very difficult to speak clearly at your normal silent reading speed.
You will probably find, if you are like most people, that you have too much material. If possible, practice presenting your report in the room where you are going to present it formally. Learn to fill the room with your voice, as described in lecture. Concentrating on the sound of your voice will also help you not to be nervous when you are presenting the report. Nervousness may make you speak faster or slower than in your rehearsal. Be prepared with a little extra material, in case you speak too fast.
If English is not your native language, and you find speaking without a prepared text difficult, or if you are overwhelmingly nervous about speaking publicly, it is all right to write your presentation out verbatim and memorize it. However, you must treat memorizing a report in the same way you would treat memorizing a play script. This means that you must memorize it with normal pauses, emphasis, and intonation, and take special care not to speak faster than the normal speech rate. If humanly possible, don't do your report by memorizing a speech--it is not the best way. Huckin and Olsen have some advice and exercises for helping non-native speakers with pronunciation and intonation [HO93, Chapter 38,]. Confidence in your understanding of your material, and taking your time will make up for a lot of awkward English and hyper-nervousness. So will substantial practice presenting your report.
Get enough sleep the night before. I have seen someone present a paper at a professional conference after running on adrenalin for a few days, then pass out and fall off the platform when he was asked a question.
Above all, remember that in an oral presentation, you must make each major point in several ways. The old saying about this is, ``First you tell 'em what you're going to tell 'em, then you tell 'em, and then you tell 'em what you told 'em.'' Of course, using exactly the same words each time does not help comprehension--what you are trying to do is to find the explanation that works for each member of the audience, and different people in the audience will understand different explanations.