I agree and upvote both previous answers, and just offer this checklist in addition:
1) Do not try to adopt an artificial inflection or tone. You'll wear it like a bad suit.
2) Do try to express your wonder and enthusiasm about the subject matter.
3) DO use personal vernaculars and colloquial "common man" phrases in your presentation.
4) If you can't describe your ideas to a nine-year-old child, you can't describe your ideas. Fit your program to your audience. Don't drill down to level 29 for investors.
5) DO express your enthusiasm.
6) DO NOT DO NOT DO NOT DO NOT...(did I forget to emphasize "do not?") read powerpoint slides verbatim to your audience. You will be dismembered and killed and otherwise inconvenienced if you do this.
EDIT: It is a very VERY good idea to do some practice read-throughs of your presentation with some kind of rhythmic music in your ears. The music is there to give you a PACE REFERENCE. Do not, however, play bad amateur techno soundtracks behind your ACTUAL presentation.
Have you ever been at an author's reading, where that author was like a runaway train careening off the rails into the ravine below? That's PACE. Ever watched an amateur golfer try to rip a tee shot and instead scuttle it just past the "ladies tees?" PACE. Ever sat through a lecture with an ancient wizard-of-the-arts who was nonethless apparently overdosed on thorazine? PACE.
Your pace wants to be conversational, it wants to seem natural and unforced. Too slow and you bore your audience and lose them. Too fast and you overwhelm your audience and lose them.