The first thing I do when I get a request at my cover shop is that I properly read through it. To get the best images, you need to know exactly what you are looking for, so it's good to be as informed as possible which is why I like to ask for the plot of the person requesting so I can know exactly what the book is about.

For example, I need to know, are the character black or white? As a black person myself, I may instinctively use black people in a book cover if the race of the characters isn't specified. Although, sometimes I use my mind to determine based on their names.

I also need to know the theme. Is it a dark theme or is it normal? Are the characters aggressive? What's their background? What's their story? Are they in the mafia? Are they werewolves? You get all these information by carefully reading through requests.

However, if you're making your own cover for personal use, you need to envision your cover. Be certain what you want. Especially because for the second stage you'll need to be specific so you need to have at least an idea of what you want.