Genre fiction is a contract. The reader sees the cover, sees the spine label, sees the back-cover blurb, and they expect a specific kind of feeling on a specific kind of schedule. The romance reader expects a happily-ever-after, or at least a happily-for-now — a 'no HEA' romance is not a daring artistic choice, it is a one-star review. The cozy mystery reader expects no on-page violence and a small-town setting where the cat helps. The epic fantasy reader expects worldbuilding that holds up if they draw the map themselves. Break the contract and the reader feels cheated, no matter how beautiful your prose. Honor the contract and they read three more of your books this month.
Literary fiction asks 'what is this trying to say?' Genre fiction asks 'is the reader having the experience the cover promised?' Neither is better than the other. They are different jobs. Literary fiction lives in MFA workshops, prestige reviews, and prize lists; it sells modestly and slowly. Genre fiction lives on Kindle Unlimited, BookTok recommendations, and the algorithmic feeds of Amazon and Kobo; it can sell ferociously if you understand the conventions of your category. Both are worthy. Only one of them is built around finishing books on a schedule and meeting readers where they already are.
Sub-genres are where the real market lives. 'Fantasy' is a meaningless category on Amazon today — there are too many books and too few readers who want all of them. But 'Cozy Mystery with a Bakery' or 'Slow-Burn Sapphic Fantasy Romance' or 'Hard Sci-Fi First Contact' is a niche where 800 readers want exactly that thing and will buy every book you write in it. The smaller your sub-genre, the bigger your share of the market that cares. KDP rewards niche dominance with category bestseller flags, ad efficiency, and the also-bought feed that does your marketing for you. Pick a sub-genre you can read for the next ten years without getting bored, because if it works, you will write a series in it.
Tropes are the load-bearing walls of genre fiction, and writers who sneer at them have not read enough. A trope is not a cliché. A trope is a promise the reader made themselves before they bought your book — they searched for 'enemies to lovers,' they sorted by 'forced proximity,' they filtered by 'fake dating.' The cover sells the genre. The trope sells the specific book. Stack two or three tropes in a fresh combination and you have written something that feels new and familiar at the same time, which is the only thing the algorithm actually wants. Trope subversion can work — but only after you have delivered the trope. Subvert the ending, not the entire premise. The reader who picked up the 'arranged marriage' book wants the arranged marriage to actually happen first.
If you do not know what to write, start with what you read. The genre you already love is the genre you will finish a book in. If you read 60 romances last year, you can write a romance — you know the beats by ear, you know what is overdone in your sub-genre, you know what your favorite authors leave on the page and what they leave to imagination. If you read sci-fi only when forced to in school, do not try to write sci-fi because the SV looks juicy. You will hate every minute and the book will sound like a person who has never lived in the genre, which is the kind of thing readers can smell. Pick the genre whose conventions feel natural to you, then niche down.