Presentations show material you collated to support a presentation you have given. Good presentations should include material that supports what you say to your audience. Here are some simple guidelines that make good presentations.
A minimal use of words (some say a maximum of 6 words per slide)
Good quality images that reinforce the point of view you are talking about
Less than five colours (excluding photos)
Complimentary colour palette
Speaker notes allow you to enter the text you will say as you present so it does not display during your presentation, but are there when you refer back to it later
Minimal use (if any) of animation and sound effects