REMEMBER that PowerPoint just like any educational document should always have an:
INTRODUCTION - start with a splash. This can be an impactful structured graphic as found in SMART ART, a dramatic well created photo, an appropriate audio/video as an attention getter. Introductions can run from 1-3 slides.
BODY - develop your story well using all the supportive benefits of PowerPoint such as pictures, photos, audio, video, shapes, SMART ART, icons, screenshots, and charts and graphs. But REMEMBER the adage "less is more". You can all too quickly overwhelm your viewers with too much embellishment. And always remember that your PowerPoint presentation, at best, should be supportive to your story; you should never read line by line from your screen presentation - this would communicate to your audience that your message is not coming from within you. Why read to your audience when they could do that on their own.
CLOSING/CONCLUSION - after conveying your message in the BODY of your PowerPoint it's best to summarize/reinstate your postulates from the BODY. For example you might say "Dogs are great companions because they love us unconditionally." or "Bike riding is not only fun but it affords us exercise and transportation." Too often I have seen PowerPoint presentations fall right off a cliff as soon as the speaker finishes with the BODY.
If you stop and think of it a PowerPoint presentation pretty much mimics our everyday conversations. Listen to your conversation the next time you run into a friend.
In the end, always remember that YOU and YOUR KNOWLEDGE about your subject is more important than the mere structural building blocks of a presentation. A well-constructed PowerPoint, created by YOU, is supportive at best when communicating your message. BUT with this in mind you should be able to create, build, and deliver, a spectacular PowerPoint presentation.