I tell my students when we're rehearsing together: Don't present to me... speak to me like we're having a conversation.
The good eye contact naturally follows.
Whether you're speaking to a room of 1 person or 1,000 the same principles apply. Look for people in the audience who are engaging with you and simply have very short (2-3 second) conversations with each of them. Your presentation will feel much more natural and you might even enjoy yourself!