Bit of a specialist subject here, as I teach this sort of thing at FE level. The first thing - and I apologise that this sounds obvious, but it's true - is practice. Then some more practice. Perform the whole presentation to yourself as many times as necessary before the big day so you are confident in what you are going to say. This doesn't mean you can't ad lib on the day - but at least you will have the nucleus of your speech clear in your head.
If you are using slides or a flipchart, don't put too much on them. They should act as a signpost for your audience and a memory aid for you. If you need to use handwritten notes to help you through, this is fine, but look at them before you speak - you're presenting to the audience, not your notebook.
I wouldn't go along with the 'focus on one person in the audience' theory as this may make the rest of the audience feel ignored. Make eye contact and vary where you make it - you'll also feel less "stared at" if you're looking at different people.
A little appropriate humour can often work wonders for getting the audience on your side - as long as the presentation is suitable for it. A presentation on increasing road deaths, for example, should probably be humour-free. Most talks, however, will benefit, but don't overdo it - it's not a comedy routine.
Lastly, but by no means least - KNOW YOUR SUBJECT!!! There is nothing, and I mean nothing, worse than hearing the dreaded words "Er, actually I think you're wrong there" coming from the audience. So do plenty of research and be as prepared as possible for the questions they may ask (they'll always surprise you at least once). This will increase your confidence no end.
Sorry about the long answer, but I hope this is of use.