If you’re going to use presentation software, there’s a basic ground floor of competence. Some of the basics:
(stolen from Timothy Burke at Easily Distracted)
1) Don’t read a slide. Ever. Ever ever. The slide is there for people to look at. You should be saying something else while the slide is there. Something longer, something fuller, something more explanatory, something expert, something knowledgeable. A slide with pure text is not ideal under any circumstances, but if it’s there, it’s there as a mnemonic designed to summarize points that you're making at greater length, with more passion, in a way that justifies and rewards the physical
presence of listeners in that room at that moment. Your lecture outline is for you. It’s not to be put up on a slide on the board and read verbatim. Ever.
2) A slide is either an image, film clip or audio that’s an impressionistic, performative accompaniment to something being said, or it’s information. If it’s information, it should be up and visible for a long time, so that the audience can write it down, take notes on it, relate it to what is being said in a verbal lecture or explanation.
3) A good presentation takes as much time to create as a good lecture, essay, or anything else of the sort. It should be practiced, edited and thought about.
4) There should be some compelling reason why presentation software is being used, something it can do which adds particular and necessary value to a given lecture. If there isn’t a compelling reason, don’t do it. Ever.
(see also Edward Tufte's three principles to avoid Death by PowerPoint)