Lots of people say to write about what you know. This is good advice, or is it?
What is “know” anyway?
How much would you need to know about something to be considered knowledgeable on that topic, and who decides this? I probably don’t know a great deal about engineering, but I could learn enough about it to make a character convincing as an engineer without needing to become one myself. I could also write about characters who are writers. I haven’t published in every genre yet, so if I wrote about a character who had published ten romances I wouldn’t be writing about something I have lived. If the measure of “knowing” means to have lived something, then that is a huge limitation of what people are “allowed” to write about, as most people haven’t lived more than one or two careers.
The best thing to do?
Isn’t writing about what we know and have lived what we should do? Yes and no. People who have had unusual experiences can benefit from that knowledge and put it into their characters. Readers will enjoy that. But…
If we wrote only about what we knew, then fantasy, science fiction, and most other fiction wouldn’t be written. The very nature of the stories we tell means that we don’t need to “know” anything to imagine them. Yes it helps to have some medical knowledge to write a realistic medical thriller, but Google is able and willing to answer most questions people can ask. You don’t need to become a doctor in order to write a medical thriller. You don’t need a definition of “knowing” to be able to write any kind of fiction.
Writing what you know best might help you get started. This can be writing about a character who has a similar career to yours, or writing in a genre you’ve read a lot of. But there’s no limit to your imagination, so take what you know, and what you don’t know, and put them together into that place in your mind where inspiration, imagination, fantasy, and reality converge.