Here are a few approaches when choosing design-y ways of encouraging people to attend your event:
Think of highlighting a detail rather than a full, spectrum image
When you can, anchor people's eyes with an action
Manipulate the sense of scale, or invert images so that when the scene is set before the viewer in real life, they are jarred into recognizing that what they see is more real than the representative image
Standardize fonts, text placement, and contextual information in order to give people a visual language they can depend on
People like people, or beautiful images. Better yet: beautiful images of people. Try to give them one or the other. Even better, try to give them both.