Cover art in my opinion is just as important if not more so than the story itself. Same with the tagline. Why? The cover image can convey everything your story is trying to tell. I’m sure at one point in life you’ve heard the proverb “a picture is worth a thousand words.” It’s because that one image can convey your thoughts, feelings, questions, statements, etc, more effectively than words can. People are visual creatures, that’s how we primarily process the world around us.
So, if you have a great story and you know without a doubt it can achieve hundreds of likes, thousands of views, and awards, you might not get the recognition because the cover art wasn’t strong enough to hook someone into opening up your story.
What makes a good cover image? Nudity works, a degree of sexual activity does too (kissing, groping, suggestive positioning. So long as you follow the no genitals guidelines). Elements that capture the heart, soul, or idea of your story. The location of where your story takes place. For example, my story Humpday (But it’s Saturday) takes place in your everyday laundry room. I found an image that captured the exact feel I was going for. You’ll also want to look into color theory too (if you really want to get into the weeds of finding or crafting cover images).
When it comes to finding images themselves, I prefer stuff that has been produced by a human. Ai images are good (especially if you prefer cartoon style images) but they tend to lack the human element if that makes sense. Hunting for that perfect image for your story is just as satisfying as writing the story itself. I usually find my images on deviant art, general search engines (I use brave), shutter stock sometimes, and porn sites.