First:
One idea per slide
Second:
Write Big. Done that? Then write bigger!
Third: Got pics?
Fourth:
Got graphs?

That's really all there is about the ppt itself.

The rest is up to you, the guy doing the show.

Speak clearly, not too quickly. Watch people at the very end of the room and try to speak to them.
Do not hesitate to pause for 2 seconds or more at key points.
If you have a powerpoint remote, use the blank screen button when you need attention. Otherwise people will keep staring at the slide and will not even care about your very important point.

if you have time, try watching one or 2 sub 10 minutes TED presentation. That will give you some examples.