I tend to gravitate to covers that are less busy, with only a few colors, bold fonts. Open spaces.
The book is gritty, takes place in Chicago and mostly in slums, so a "rougher" looking cover would fit.
When I have been formatting my doc I have used the font Dead Kansas. That's not a requirement, but it could give you an idea of where my head has been at when picking fonts. I think I would prefer a sans serif font.
The title, The Bear Trap, is figurative and refers to one part of the book where one man is explaining that a God would allow seemingly bad things to happen because there is an ultimate purpose for these bad things. He equates it to a person releasing an animal from a bear trap, and how you would have to push the animals leg further into the trap to release it, thereby causing short term pain to ultimately set the animal free. So there are no literal Bear Traps in the story.
Typically I wouldn't want literal imagery on the cover, but since the Bear Trap is already a figurative element, I am open to seeing covers with actual Bear Traps (as long as they don't make the book look like a hunting/forest thriller or something).
Another piece of imagery that is not required but plays a role in the book is the missing girl. She has a medical condition that causes one of her pupils to spread into the whites of her eye (just one eye). So that is potential for an image. However, I would not want a full shot of a girl, or her face. If you use the eye with the black spreading through the eye, it should be a close up of an eye.
Ultimately, the book is about the main character uncovering a large black market, much like black market organ trading, but they are harvesting genetic material to be used for gene editing. So this begins as a missing girl case but turns to something else. Images indicating a larger conspiracy (without giving too much away) could work.
When looking at covers, I seem to be drawn to covers where the font (or some part of the cover) is made to look like it is cut into the cover, or created by negative space.
I will include some covers I saved that caught my eye for one reason or another.
I am still formatting the paperback version, but I would estimate it will be around 370 pages. On cream paper that is .925 inches for the spine.
Print cover should meet all Amazon Direct cover guidelines found here -https://kdp.amazon.com/en_US/help/topic/G201857950#filecover