Organize your thoughts and your message...and create an outline.

Powerpoint is such a great tool in developing a talk but it can be a crutch that allows you to skip important steps--steps you SHOULDN'T skip. Think back to your college days and grab a notebook to plot out an old-fashioned outline with a beginning, a middle, and an end. Figure out what message you want to deliver--and that's your beginning. TELL people that's what they are there for. Then come up with your supporting points, in outline format--and put only brief bullets on a slide. You want your slides to trigger your thoughts and give people an anchor while you are talking--you never want them to be reading cumbersome, clunky text while you're trying to get a point across. Nor do you want to read to them...unless it's a presentation to the pre-K set. Finish by reinforcing your message and telling people again what you'd set out to tell them at the beginning.

I recommend: I found a good source for remembering the basics of an outline through Purdue University.
Unless you're adamantly opposed to it, it's great to do this step on paper--or even index cards; then you can sort and re-arrange your points for maximum impact.

Include multi-media

If it's done right, a relevant movie clip or cartoon can quickly convey your point--remember, a picture conveys 1000 words! But be careful not to fall into the trap of spending 20 minutes of a 30 minute presentation showing movie clips--your audience may feel entertained, but it's overkill and dilutes your message entirely. One or two quick, concise clips keep people tuned in and reinforce your point well--especially if correctly placed, maybe at the beginning and end of your presentation. Make sure any copyrighted material you have is acceptable to show--often, you have to pay for rights to show clips or even photos. Downloading a picture from the web is easy, but legally you have to pay to use it (or you'll often have a watermark printed across it). And of course be very familiar with your clip--you'd hate to hear an inappropriate word or phrase slip out--in front of an audience of potential clients!

I recommend: A group like BZ Rights can help you with rights for multi-media content. If you're trying to come up with some ideas for a good tie in, find a movie buff or surf through sites like the Internet Movie Database...I once went on a chat board and posted "Who knows a great movie with an elevator scene?" and within 30 minutes had 4 solid suggestions. And photo sites like Getty or Corbis are fairly easy to use and properly purchase the rights to pictures.

Do it right.

It's pretty easy to master the basics of PowerPoint. But then there's that next step--and if you're working on a presentation that is going to represent you and your business, especially one that you'll deliver repeatedly (maybe with minor changes), it may be worth it to retain the services of an expert. A marketing consulting company can help you integrate your presentation into your overall marketing message and brand (full disclosure--that's one of the things my consulting company specializes in!) Another route is to find a college student who's probably more familiar with PowerPoint than he/she wants to be to help you put the presentation together--again, this is once you've gone beyond the outline step. Then, make sure you outline notes and key points you don't want to miss--but try to avoid writing them on slides, as you'll tend to use them as a crutch and may get held up in trying to remember one specific point when delivering your presentation.

I recommend: A site like Craig's List is a great place to post a simple want ad for project work like "I need help creating a professional, standout powerpoint presentation". Make sure you're clear on how you'll be delivering it--ie, don't have someone add in a lot of music or graphics clips if you won't have someone to help you play them or if you'll be playing sound out of a tinny laptop speaker. 
Putting a little bit of money into a presentation you'll use repeatedly is a good investment--especially because no amount of money will reverse a bad or "cheesy" impression left by a poorly done presentation. But you may be surprised how reasonably you can get someone, especially someone who's freelancing, to help you.
And it goes without saying: Spellcheck.

How do you get to Carnegie Hall?

Practice, practice, practice. Take the time to deliver your presentation to your spouse, your kids, the mirror. The best thing, if you can, is to get someone to videotape you and watch it--you'll be shocked at things you do (like shuffling, shifting, etc) that you don't even realize. Unless you're extraordinarily comfortable in front of people you may want to minimize your motion as it often comes across as nervousness, even if you're trying to appear comfortable onstage. Professional courses (like Dale Carnegie) are great but time-consuming and pricey, and as a graduate of such a course I can say that the most valuable thing I took from it WAS watching myself on tape. Trust me, it can be excruciating ("I don't really sound like that, do I?" but it is well worth it and will make your final presentation outstanding.

I recommend: Groups like Toastmasters give you a lot of practice in public speaking in a variety of venues and many a corporate CEO will credit such groups with their ease in front of people.

Look forward to it.

Someone gave me this advice before my first big business presentation. I was speaking to a group of 100 or so and I was so nervous. "Look forward to your presentation", I was told. "You've got to be kidding!" I said. "I'll be counting the minutes till it's over!" But I tried--it sounds Pollyanna and silly, but the simple act of thinking of the presentation as a good thing, not something to dread...can make a huge difference. I did try to look forward to the talk--and after delivering it I found myself wishing I could do it again!

I recommend: Think of presentations you've seen or speakers who were exceptionally good. They practiced to get where they were--very few of us are natural-born speakers. The more practice you get, the better you'll be--and a positive attitude can make the difference. Books about great orators may give you inspiration...