Okay, my point is ( specific to me), as I mentioned earlier, that when you "create" an audience for a FB ad you're prompted to target particular gender, age, location and "special interests". It's that last parameter that is most important, while the others can be tweaked ( for example, you would not target "men" if you're promoting a romance book, and it's reasonable to perhaps have an age cut off of above ... maybe 30?).
Trying to narrow the "Special Interests" into a target audience of "not too broad", meaning smaller and focused, isn't easy because you always hit popular categories like Thriller, Mystery or Cozy, etc., and it means your ad is competing in an enormous pool.
In the past, Horror was buried in this ridiculous and irrelevant genre of "Urban Fantasy", but recently FB has given it a niche Horror Fiction category of its own ? even separate to horror movies, series and so on, so FB has suddenly made my targeting much, much easier.
For Tim, something like "Military Sci-Fi" might now exist, or "Sci-fi action" ... anything that pinpoints your genre within the broader, huge genre of simply science fiction.
CPC ads have a simple rule. If you're writing James Patterson-esque novels and you're competing against JP ... you're cooked. You won't have the budget balls to risk the same level of spending just to play on the same page. But if something in your narrative allows you to compete in a much, much lesser narrative concept like, "James Patterson Bakes Cakes" and you kind of sneak into his target audience through a loophole, your CPC can be much reduced.
Apologies, I'm on my tablet and it's difficult to explain in full.
Bottom line (and this has always been the case) targeting a much smaller but avid audience is always better and cheaper.
