Your idea for a story is selected, jelled, and ready, but where does it all happen? Using artistic imagination, it can be anywhere in the world, real or imaginary, somewhere you’ve visited or want to. If it’s home, you’re set. For other settings, more work is necessary. Research the area – the less familiar you are with a city, foreign region, or ocean beach resort, the need to investigate it increases.
Readers are known to criticize discrepancies in settings. Accuracy is one way of eliminating criticism, the other is making up a setting. As the creator of the location, you have freedom unfettered. Louise Penny in Still Life used the village of Three Pines, then again in subsequent books. If you’re writing a series keep in mind that what’s there stays there unless you change it. Because it’s fiction, combinations of real settings and envisioned ones work too. Knowing your readership helps determine if you’re writing augmented murder mystery fiction or fantasy. My Lieutenant James’ work is in New York (real) though I moved his residence to Winburg ( made-up) for The Numbered Cups Mystery.