Write what you know works insanely well if you’re a doctor, lawyer, dietician, nutritionist and you’re writing a non-fiction book about the field you have a degree in. It means you know what you’re talking about and can be trusted with information.

It works insanely well if you’re a lawyer, cop, detective, judge, and write crime thrillers. They know what they’re talking about. Same for doctors writing medical thrillers.

Michael Crichton wrote the pilot script of E.R. and many thereafter. He was one of the executive producers of the show even after his death. He went in a completely different direction with Jurassic Park. But it’s still about DNA and how we shouldn’t use it to resurrect beings that cannot exist in this timeline. These two aren’t the only things he wrote using his medical knowledge. He also wrote The Andromeda Strain, Coma, Five Patients, and A Time of Need among many others.

Jackie Collins wrote about the star-studded world of celebrities she lived in. Her friends, and even those she didn’t know, loved to accost her at parties and tell her all their juicy gossip. She then mixed it all together and wrote characters that reflected the people she knew. She lived this world. Her older sister Joan was a famous actress, once engaged to Warren Beatty. Jackie’s father was a theatrical agent. Her second husband, Oscar Lerman, co-owned art galleries and nightclubs where all the stars hung out. Jackie had every actor, singer, musician on speed dial and they all called her up to tell her the salacious gossip from the parties they attended. She lived the life!

Writing what you know works well for those who know it, for the rest of us, we need to make it up. Don’t worry about inventing a world that doesn’t exist, it’s fiction, after all. And don’t worry about using real places, towns, cities as the backdrop, just do your research and have a basic knowledge of streets, tourist destinations, and the like, so you don’t look like a fool for not doing basic research. And if you aren’t in law or medicine and write crime or medical thrillers, really do your research, because someone who is in those fields, will pull you up on your lack of knowledge concerning guns, laws, crime scenes, and hospitals.

Don’t let the phrase “Write What You Know” put you off writing. You’re creating a fictional world after all.