So I recommend choosing an uncluttered, high-contrast theme (such as Gradient or Showroom in Keynote, or Twilight or Clarity in PowerPoint) and, where practical, limiting each slide to a single element (such as an image, graph, quote, or question). Select visuals that support, explain, or clarify what you say. They're on the screen to help your audience understand and remember your talk, not to serve as cues or reminders of what you want to say — that's what Presenter Notes are for in Keynote or PowerPoint. (In Keynote, you may need to choose View > Show Presenter Notes to see the area at the bottom of the window where you can enter them. In either app, these notes appear on your Mac's screen during a presentation only when your presentation is on a secondary display.)
Consider your audience and purpose
That said, every audience and presentation is different, and sometimes the sort of minimalism that's great for a motivational talk is not what you need. So keep listeners' expectations in mind as you prepare your presentation.
For example, if your audience is made up of corporate VPs and your topic is last quarter's sales figures, everyone will be expecting to see the facts and numbers — not just hear about them. If you're teaching a programming class, your students need to see sample code on the screen. If you're introducing a new product, your customers want to see photos and feature lists. In these and many other cases, the stuff you put on screen is far more than window dressing, and it may sometimes require showing lots of text. There's no shame in that, but still: keep that text as brief, readable, and relevant as you can.
Speaking of text: Bulleted lists may be boring, but there's nothing inherently wrong with them, and sometimes they're exactly what a fact-heavy presentation needs. If you do use bullets on slides, make sure the text is large enough that people in the back of the room can read it and be as concise as possible. I nearly always set up builds to display just one bullet at a time so that the audience isn't tempted to read rather than listen.
To do this in Keynote, select your bulleted list, click Animate on the toolbar, click Build In, click Add an Effect, and then select one of the Appear & Move effects. From the Delivery pop-up menu, choose By Bullet. In PowerPoint, select your bulleted list, click the Animations tab, and click an entrance effect. Then, from the Effect Options pop-up menu, choose By Paragraph (the default).
These tips might seem to minimize all the effort you expended learning how to use your presentation software of choice. But, as I say, the software isn't the point: the presentation is.
Sign up for CIO Asia eNewsletters.