Rehearsal
Rehearsal is a vital part of preparation. You should leave time to practise your presentation two or three times. This will have the following benefits:
you will become more familiar with what you want to say
you will identify weaknesses in your presentation
you will be able to practise difficult pronunciations
you will be able to check the time that your presentation takes and make any necessary modifications
So prepare, prepare, prepare! Prepare everything: words, visual aids, timing, equipment. Rehearse your presentation several times and time it. Is it the right length? Are you completely familiar with all your illustrations? Are they in the right order? Do you know who the audience is? How many people? How will you answer difficult questions? Do you know the room? Are you confident about the equipment? When you have answered all these questions, you will be a confident, enthusiastic presenter ready to communicate the subject of your presentation to an eager audience.