The quintessential business pitch: the difference between the life and death of your startup could come down to this single element. At a more basic level - effectively communicating the value of your business to an investor with a limited amount of time and visual-aids is more critical than you may think. Of course, there are a thousand ways to kill a startup; today, I'm going to focus on this one.
First, to qualify myself a little: to date, I have delivered well-over 25 business pitches to drastically different venues/audiences over the past 4 years, and each of them has been different. I have been (and still am) in a constant state of pitch-perfection - continually biting the bullet and tossing-away slides that were the work-product of what probably amounts to months of my time. It is only by going through this (painful) process that I've collected a number of do's, don't and general tips and tricks for an effective pitch:
Stop focusing on the tools and start focusing on the content. Yes, yes, Powerpoint is the bane of our existence, so everybody needs to go waste time climbing the learning-curve to make fancy visual roller-coaster rides that will make your audience dizzy (cough, cough, Prezi...cough). Remember: nobody's investing in your visual aid, they're investing in your company - stay focused on making the content count!
Powerpoint isn't so bad anyways. If used properly, Powerpoint is great. Not every investor wants to download some fancy viewer to look at your pitch. Just about everybody has Powerpoint, and absolutely everybody can read a PDF. If you want to be smart about it, make a presentation that can easily be read/understood in PDF format, and you'll be ready for anything!
Speaking of Powerpoint....let's talk about animations. Just don't do it. If you absolutely need two visuals under the same heading, here's the trick: just copy the slide and make a second one with the same heading (nobody will notice if you had an animation or just went to the next slide, AND this is totally PDF-able)! This way, when you're running your presentation off some machine that decided to auto-update during your presentation, you don't have to experience the embarrassing moment of pushing the clicker like you're playing Super Smash Bros. to get the animation to appear (and then the next moment when everything decides to work and you skip 10 slides ahead...I've been there, it's nasty). Just say "NO" to animations!
Let's talk quantity. You've probably heard of Guy Kawasaki's 10-Slide Rule. Fundamentally, I love Guy and his advice - it's great. But if you need more than 10 slides, don't freak-out. In fact, I don't count slides anymore. I use whatever amount I need to portray the supporting visuals necessary without ending-up with 10pt font on my slides. Guy agrees small fonts are a no-no, but what he doesn't really say is that in order to keep your fonts big, you may have to split slides into 2 like I mentioned above.
Now, quality. This is a big one. A mentor of mine once told me that your audience can either listen to you, or read your slides, not both. So make sure they are complementary, not redundant (I'm assuming you already know to NEVER, EVER read your slides...so that shouldn't even be a consideration). Also be sure to consider both visual and word-thinkers (so have a mix of supporting visuals and language on your slides). I've seen a trend towards slides with big pictures or single-words; I get it, it's sexy, but you're losing part of your audience unless you use both (sexy pictures + sexy words - duh!).
Practice makes perfect. I have a pitch coming-up April 14th. I started practicing March 1st. For the first few weeks, I'll do every-other day. This gives my brain time to process new information, come-up with new ways to say things, and add slides as-needed. You want this process to be analogous to boiling-out the impurities in your pitch. When you start, it will be messy, way too wordy, too long, and indirect. Over time, and with (a lot of) practice, you'll start to see the impurities yourself. You'll determine the perfect way to say "X", or decide "Y" isn't really important. You'll rearrange slides in such a way to make the pitch flow and build a good story. You can't get to that perfect boiled-down/pure pitch without repetition. If you're looking for a number, my general rule (and many others agree) is 20 x makes near-perfect.
Don't memorize! Don't back yourself into a corner by memorizing. If you slip-up during the pitch, you'll be lost and look like a bozo. You can also end-up sounding like an incompetent robot that doesn't know his/her material well-enough to speak without a script (ouch! I know, right?). It also makes it much more difficult to make those last-minute changes the night before the pitch (because your Marketing-guy just gave you a new slide that "has" to be in the pitch).
So I should just wing-it? NO! I always tell people to envision a scale where 0 is "winging-it" and 10 is "memorize it" - you want to be at a 15. By that I mean, go beyond memorization into comprehension. You want to understand what your audience is actually hearing when you show that slide or deliver that sentence, and you want to make sure they're understanding what you want them to.
To write or not to write? I do NOT write-out my pitch first. To me, it's wasted-time. Things never sound the same when spoken out-loud as they do when you write them down. So I practice out-loud from the very beginning, and figure out what sounds good. You should NEVER be reading your pitch anyways, so since your audience is going to listen to your words, you might as well start there.
How about practicing in-front of my parents/friend/etc? I know, I know, many people give advice to "practice in front of your mom or grandma, and if she gets it, anybody will". While this can be marginally valuable at helping expose areas of your pitch that don't make sense, I'd caution against it. Nobody understands your business better than you. Your goal is to communicate that as effectively as possible to your audience. When you start taking advice on how to structure your pitch from an "outsider" that doesn't understand you business the way you do, you run the risk of convoluting your message even more, and making things worse.
Bottom Line: watch other people pitch online, read articles on how to deliver a good pitch, but at the end of the day, it's your baby, and only you can craft it perfectly - so practice, practice, practice! Happy pitching!