The 10 / 20 / 30 Rule of PowerPoint (by Guy Kawasaki) ---> How to succeed in making good powerpoint presentations !

From the link: http://blog.guykawasaki.com/2005/12/the_102030_rule.html#axzz28kPV4vZf

A PowerPoint presentation should have ten slides, last no more than twenty minutes, and contain no font smaller than thirty points. 

• Ten slides. Ten is the optimal number of slides in a PowerPoint presentation because a normal human being cannot comprehend more than ten concepts in a meeting. If you must use more than ten slides to explain your business, you probably don’t have a business.
  
  The ten topics that a venture capitalist cares about are:
  
  1. Problem
  2. Your solution
  3. Business model
  4. Underlying magic / technology
  5. Marketing and sales
  6. Competition
  7. Team
  8. Projections and milestones
  9. Status and timeline
  10. Summary and call to action
• 
  Twenty minutes. Present your ten slides in twenty minutes. Sure, you have an hour time slot, but use 20 only. People will arrive late and have to leave early. In a perfect world, you give your pitch in twenty minutes, and you have forty minutes left for discussion.
• Thirty-point font. The majority of the presentations that I see have text in a ten point font. As much text as possible is jammed into the slide, and then the presenter reads it. However, as soon as the audience figures out that you’re reading the text, it reads ahead of you because it can read faster than you can speak. The result is that you and the audience are out of synch. The reason people use a small font is twofold:
  First, that they don’t know their material well enough;
  Second, they think that more text is more convincing.
  
  Force yourself to use no font smaller than thirty points. I guarantee it will make your presentations better because it requires you to find the most salient points and to know how to explain them well. If “thirty points,” is too dogmatic, the I offer you an algorithm: find out the age of the oldest person in your audience and divide it by two. That’s your optimal font size.