A common, and somewhat ill informed, piece of advice is to make lots of eye contact with the audience. Fair enough, you do want to let the audience know, that you know, that they are there. I even like posing questions to the audience to engage them. Remember a slide presentation is a passive experience for the audience and people don't learn well in a passive mode. Yes make eye contact.
Still eye contact can be overdone. Your job as speaker is to help the audience understand the slides. When you are talking about a particular part of a slide you need to use the pointer and point to that part of the slide. That means turning away from the audience and looking at the slide. So another way of thinking about it is that both the slide and the audience require your attention. You need to go back and forth. Eye contact with the audience 100% of the time means they don't know the relationship between what you are saying and your slides.
What doesn't require your attention are notes that you may have at the podium. The slides are your notes. They are the guide for what you should be talking about.
