The first thing I recommend doing with any presentation is ask yourself what is the purpose? Write the purpose down on paper. You should be able to write an effective purpose statement with 1 or 2 sentences. Generally it should be to persuade or inform. Being prepared is a great feeling and the more prepared you are going into the presentation, the more confidence you will have. Of course, work is equal to being prepared. Your audience could be doing a ton of other things, and it takes only just a few moments of you hesitating or fumbling with the slides for them to mentally check out.
Start your presentation strong. Share something that will be of value to your audience. Maybe it is a story. Stories captivate, but your story needs to be well thought out and needs to benefit your audience. Time is money and make sure you thank your audience for their time they sacrificed to be with you.
Another thing to ponder is what would you do if the projector or computer failed during your presentation. The show must go on and being extra prepared with notes and handouts or stories will prove to your audience that you are the right person to present.
As far as design of the slides, the basics of any decent presentation should have strong contrast between the background color and font color. Use fonts that are easy to read and are aligned. The space between objects helps create a clean look. Sometimes less is more. Let someone else you know proof it.
During the presentation smile, use your hands, be energetic, make eye contact with your audience. Above all, be passionate about your subject. This is stuff you can’t fake. You know if you have it, so will your audience. Finally, don’t use more time than what is agreed upon.