Look for white space
Last week, 500px shared 6 tips for photographers to better sell their photos.
These tips are great to understand how to choose the right banner image for a website - for example, images that tell a story, or that let you write some text without spoiling the beauty of it.
"Full-screen photo backgrounds are a very popular design pattern. They require an amazing photo to help shape the message; however, we still need to have room for headlines, bylines, and buttons."
4-mn read: Dear photographer (Medium)
Edit: Since then, I've written a full post on how to choose the best images.