Images must reinforce the message and speak for themselves. Don’t use them as a space filler!
Think about what to use beforehand: images, video or an infographic. Do you want to present a lot of research data? Then include an (interactive) chart.
Don’t use tables to create content, for example, because you want to have an image on the left and text on the right or vice versa. For layout, use the content management system’s fixed features only.