There was piece of advice that I had before I started writing and that was 'write what you know about'.
My first Crime Thriller was about a reasonably young man being taken for a very expensive ride by his wife and he uses his skills learned in his former employment to commit fraud and recoup the money that it cost him.
The necessary skills were those of a studio photographer, a printer and the operational side of Travellers Cheques. I had those skills and employed them in the novel. In the reviews of my book, it is the details of these processes that make the story real.