There is so much good information about the craft of writing out there. Here’s an article written by Marcia Rosen, Writing Mysteries: Is It a Mystery? In a very concise manner Ms. Rosen explains the basics of writing a mystery. It appeared in the June, 2018 inSinC, The Sisters in Crime Quarterly. If you’re interested in mystery writing this is a wonderful international association. Wherever you live, there will probably be a local chapter near you.
Check out their website at http://www.sistersincrime.org