A few things you should keep in mind when you present:

• Start with a title slide with nothing other than the title - to make sure people actually look at you when you are talking, rather than read the slide
• Keep the slides to a minimum, to prevent people from reading instead of listening to you
• Make sure you are looking at the audience, rather than looking at the slides - this is one of the bad things of having a laser pointer in presentation for example, is that you tend to show your back to the crowd (or a profile at best), instead of looking at people and establishing eye contact with people one after the other
• Watch your body language: no hands tied in front, as if you were trying to protect yourself from the crowd
• Speak loudly (practice in your car by yelling your story to yourself), and always make sure that people in the back can hear you
• Repeat questions for everybody to hear, even if there is a microphone. This is a good way to buy time while thinking of an answer, and it is also useful if not everybody in the crowd could hear the original question
• Summarize the key points for everybody at the end of the presentation, so that people remember what you wanted them to remember from the presentation
• Always finish with a blank slide (or title slide showing Q&A), so that people are not distracted when you are answering question
• If you are presenting to investors, it is nice to finish by invitation to join you in this great venture you just talked about, instead of just asking for their money...