Plunge Into the Unknown
A new book is full of unknowns for a reader. When a reader starts your mystery, you can help them get involved by giving them the keys to what will follow. Your reader will know right away this is the story for them.
Everything about your story is unknown to your reader. Give them a time, a place, a sleuth to love, and a murder to solve. Get your reader into the story.
For new novelists, getting to the point is throttled by all the ideas you have in your head and all the things you know about the story. Your main goal at the beginning of the book is to engage the reader.
Everything is an unknown to a reader as they start your mystery, except that they are beginning a mystery novel. Reassure the reader that the story you promised feels like the genre they want, gets your protagonist in action right away, and delivers a dilemma that keeps them reading for more.