A good set of slides can enhance your presentation immeasurably — but they can also be ineffective or even destructive. Don't let your presentation be a victim of "death by PowerPoint"!
There's an unfortunate perception among some people that using slides (commonly referred to as a "PowerPoint presentation", although there are other platforms that you can use) makes any presentation better. That's simply not true. While some presentations can be enhanced with slides, they're unnecessary in some cases and can actually detract from your presentation.
For example, I was doing a training program for a major electronics firm once, and as I was preparing my program, they asked about the slides I would be using. I explained that I didn't need slides for what I was going to be doing. In fact, they would be an unnecessary distraction, and the training wouldn't be as effective.
The manager replied "Oh no, you have to use slides. It's corporate policy that all our training programs must use slides!" Since they were paying my fee, I acquiesced and provided them with a nice set of slides. But the resulting program didn't work nearly as well as if I had been allowed to present the material the way it needed to be presented ― without slides!
Of course, this doesn't mean that slides are always bad either! If you're explaining a complex subject, showing your audience a diagram can make it more understandable. If you're saying something that people may need time to think about, putting it on a slide is an effective way of giving them that time. And like the spoken word, slides can often be used for humorous effect.
Basically, I suggest that you edit your slides in much the same way that you edit your speech. (You are ruthlessly editing your presentation, aren't you?) Examine each slide individually and ask yourself if it contributes to your presentation. If it doesn't, take it out! (And if you end up without needing any slides at all, you've answered your own question as to whether or not you need to use slides.)
Once you've determined that a particular slide is necessary, the next step is to determine if the slide is as effective as it could be. In general, images (photos or diagrams) are more interesting than words. And if a slide contains more than 8 or 10 words, it can be difficult for your audience to read.
Putting together an effective slideshow can almost be as challenging as developing your presentation itself. Fortunately, there's a wealth of good information on the Internet about developing effective slideshow presentations. So IF (big "if") you decide that your presentation will benefit from having a slideshow as part of it, search for "slideshow presentations hints" and see how you can make your presentation better.