I have a question about writing in two genres (having seen several times that you recommend against it for authors starting out, and suggest mastering one before adding the other).
As I see it, there are two types of genre: genres that talk about the plot, and genres that talk about the setting. Mystery, for example, defines a kind of plot and talks about what will happen. Historical defines a kind of setting and talks about where it will happen.
I can see the problem with trying to combine two type of plot genres, especially for new writers. If you're still learning how to plot out a good, compelling mystery, I imagine it'd be really hard to also figure out how to plot out a good romance, and then even harder to figure out how to tie those two plots together and balance them well. So I totally get that.
But it seems to me like if you have a mystery, it has to be set somewhere. Why not make it historical? If you don't make it historical, what is the non-setting that means you're not writing in two genres? Would it have to be modern day where you live? And similarly, if you are going to focus first on mastering historical fiction, what sort of plot would work for not combining two genres?
Or did you have more in mind trying to combine mystery and romance when you don't yet know how to write mystery or romance?
And are you ever tempted to make up new genres with esoteric rules to confuse and bewilder the authors who keep asking you about genres?
(Sharkian Fiction: The protagonist must be named Felix Buttonweezer, and he must be chased by a shark throughout the story. If he is chased by a dolphin, please see Delfine fiction. There should be at least three but no more than seven instances of key words used throughout the story (letters in consecutive order, but not necessarily in the same word); the words must be chosen from advertisements in the New York subways. Always submit on a Tuesday, and only to agents whose name begins with an F, Z or Ö.)
Thank you for your patience!
I'm not sure why you think there are only two genres, and that they are plot and setting.
That is simply not what genre is.
Genre is used to describe a certain kind of book. Genres are: crime, science fiction/fantasy, and romance.
Historical is NOT a genre. Plot is NOT a genre. Nor is setting.
Historical is a category. Any genre can have books that are historical (although historical science fiction defies easy explanation.)
YA is a category, because any genre can have books that appeal to young adult readers.
The reason I tell you to focus your writing in one genre (ie write crime novels, not crime and a romance and a fantasy novel) is because you need to be familiar with the books in your genre if you want to write something fresh and new.
That means you know the canon. Canon means the books that came first. Those are books that you see on lists like "100 Best Crime Novels of All Time." Unless you know who murdered Roger Ackroyd, you're operating with a severe handicap if you want to write crime.
It also means you know who's leading the pack these days. You want to read the nominees for Best Novel for the Edgar Awards, and you certainly want to keep up with what is selling well, and also what doesn't seem to be selling at all.
It's hard enough to do that in one genre, let alone two or more.
The larger problem is this: you're operating in a vacuum of knowledge here. You need to spend some time learning the vocabulary of your trade. It's essential that you know what genre and category are, and not just decide on your own.