I am still figuring that out myself. My current project is a fantasy-themed visual novel for which creating backgrounds is super easy. You just pick a certain style, for example "by Greg Rutkowski" and put that in any prompt.
Normally you want to reuse your backgrounds as much as possible to not blow the budget but thanks to AI I can be much freer with my writing. Of course the important backgrounds should be remade by hand at some point but for prototyping they are great. Character art does not really work beyond concept art as you normally need different poses for a character and you are very specific about what you want, again not a strength of AI.
My advise would be to play to its strength, if you can: Horror works really well. Outdoor scenes work better than indoor.
