A common error that people make when putting together presentations is adding too much text to each slide. Also, reading everything straight off the slide is boring for the audience–you need to interact with them, not the screen!
It’s important that you have enough information to cover your topic thoroughly, but not all of it has to be placed on the slide. Instead, add small pieces of key information on the slide, and expand upon them while you talk. If you can’t remember every word, write down things you want to talk about on index cards and refer to them while you present.