I am a big believer in telling stories through a collection of images, be it in a zine, book or exhibition. Let's call it a project: a vision we have, a message we want to deliver, something we want to tell.
Generally speaking, I want to make all the images in a project look very similar, to have the same aesthetic. Otherwise, it might confuse the viewers.
Think of a book: all the words, letters and sentences are the same color and size. Only titles are different to make them stand out, to mark an end and a beginning. All the pages follow the same layout as well. It'd be too distracting otherwise.
There are a few things we want to keep constant or very similar: if an image is monochrome or color, the amount of grain, the contrast, the aspect ratio.
We can emphasize the importance of an image making it bigger, spanning through two pages, for example, or even changing the aspect ratio just for that one.