Top Rules for Mystery Writing
More than any other kind of genre writing, mystery writing tends to follow standard rules. It is because readers of mysteries are looking for a particular experience. These readers are looking for the intellectual challenge of solving a crime before the detective does, and they want the pleasure of knowing that everything will come together in the end.
Of course, the best way to test the rules of mystery writing is to read many books in the genre. This way you can see how other writers use the rules, and how they're able to get away with breaking them. But before you attempt to break the rules, read the rules below and see how your work adheres to the rules, and how it deviates from them.
In Mystery Writing, Plot is Everything
The Crime Should be Violent, Preferably a Murder
For many readers, only murder justifies the effort of reading a 300-page book while suitably testing your detective's powers. However, it's worth noting that other types of violence (such as rape, child molestation, and cruelty to animals) are taboo enough to warrant a mystery novel.
The Detective Should Solve the Case Using Only Rational and Scientific Methods
Keep in mind this oath written by G.K. Chesterton for the British Detection Club, "Do you promise that your detectives shall well and truly detect the crimes presented to them using those wits which it may please you to bestow on them and not placing reliance on nor making use of Divine Revelation, Feminine Intuition, Mumbo Jumbo, Jiggery-Pokery, Coincidence, or Act of God?"
Wait as Long as Possible to Reveal the Culprit
People are reading to find out, or figure out, the whodunit. If you provide readers with the answer too early in the book, the reader will have no reason to continue reading.