It may not be obvious from the page dcnick96 pointed to, but it is very important that PowerPoint slides be very brief, concise, and without fancy formatting. Cool font effects and paragraph formatting are distracting and may count against you to the extent that they annoy the judges. Also, there should be very little text on the slides. Here is a good essay by Don Norman:http://www.jnd.org/dn.mss/in_defense_of_p.html
Some people think PowerPoint is itself an abomination:http://www.edwardtufte.com/tufte/powerpoint
I took a class from Don Norman at UCSD, back in the days of dinosaurs, and I have attended Tufte's excellent seminar (I have several of his books as well). I'd say Don Norman is a deeper thinker, if I had to choose. Your mileage may vary. In any case, Don Norman's tips should be your guide every time you create a PowerPoint presentation.