First off, 'Believe in yourself and your audience will too'.
Now, to get into the basics, you need to know the subject matter. You need to know why and what you're presenting and your audience. After you know what it's about, a good design in your presentation is key. Usually it's good to start off with a grid that will apply to all your slides. Lucky for us, most presentation creation programs come with this built in. If all else fails, get inspiration from other presentations or blogs.
Next, the link delves into presentation skills. One is to provide as many visual aids (pictures, graphs, tables) as possible; it is proven that people take in about 55% of the information and retain it longer if the material is visualized rather than text.
The next step is to rehearse; if you've never went through this, it will be obvious by the pauses you make to orient yourself on the spot. Rehearse about four times and in front of an audience that you know can give you valid constructive criticism. Also, memorize your lines and if you don't have an audience to practice in front of, record yourself.
When arranging information in your presentation, remember that the audience will remember three main points. Make those points your introduction, middle and end. In addition, use a list of three whenever you can; less is more.
Lastly, if you can, incorporate some appropriate humor into your presentation. Not only will it be an icebreaker for your audience, but it will also loosen you up.