It’s OK to be nervous. In fact, it’s probably a good thing. If you are very calm before a presentation, you may be underestimating the difficulty of your assignment. If you’re calm because you consider the topic an easy one (a “no brainer”), you may not project enough interest in your subject.
If you’re not nervous, you may have a hard time projecting the energy and enthusiasm that you will need to win your listeners’ attention. Nervousness can be a tool to communicate enthusiasm.
Channel your nervousness by forcing yourself to speak clearly and to make eye contact with your listeners. It cannot be stressed too often that the element of balance is important in delivering a speech.
Come across as too relaxed and you will sound a little bit bored. If you are bored, then the audience will expect to be bored as well, and they will need very little excuse to start mentally running through other things that they have to do later on that day.
Conversely, if you come across as too nervous, they will wonder why you are giving the presentation rather than someone “competent”. Also remember that although eye contact with your audience is good, staring at them will just make them apprehensive – or worse yet, amused.