Sooner or later, the novice writer is given these words of advice: "write what you know". To a certain degree, it's sound advice. If you can get inside the head of a character, they are more believable. A scenario reads as more 'real' if it appears the author is writing like they know what they're talking about.
But if you start writing young, this advice can seem a bit daunting. At 16, you don't know much (even if, at the time, you think you know everything).
I do have a tendency to write about what I know, but it's largely down to a very literal nature and being too lazy to do research. When I started writing stories as a child, I was writing about myself - literally. I enjoyed writing stories about the wonderful - and extremely fictional - adventures of myself and my best friend Helen and our respective younger sisters. I guess I thought my real life was far too ordinary, so I made up something far more exciting.
When I got to about ten or eleven, I started writing stories about fictional characters. But they were still largely about me - they were always girls the same age as me, with the same character traits. At the time this seemed a perfectly natural thing to do. I had no experience of how someone who wasn't me might react in a given situation, so all I could do was write about the character in the same way I would react to the situation.
As a writer, you have to learn how to put yourself in someone else's head. You might react in a certain way, but someone with a different background, with different personality traits, might not. That was a lesson I found difficult to learn, as a young writer. One of the most frequent criticisms I received about my writing when I was in my teens and early twenties was that my male characters came across as flat and unbelievable. Even now, I sometimes have trouble writing men. Well, having never been one, I find them hard to understand sometimes. But I digress...
"Write what you know" is an important lesson. But part of that lesson is learning to understand what you don't know, so you can write about it effectively. Reading other writers can often help, especially reading in genres you might not necessarily be drawn to. Talking to people is a valuable source of information. I see parties as more than just social occasions these days. Sometimes I get chatting to someone I've just met and find out they work in a career that might actually be a useful source of information. If it turns out they are a police officer or coroner or even undertaker, for example, chances are I'll try and get their email address before I leave the party.
I still get nervous about straying outside my comfort zone as a writer, but sometimes it's necessary to stretch one's writing. When I wrote SUFFER THE CHILDREN I had to get inside the head of a young woman who'd been brought up by a neglectful mother addicted to drink and drugs, on a grotty council estate, repeatedly abused by a variety of men who passed through her mother's life. This was all daunting stuff, way beyond my own sphere of experience. But most people who've read the book and fed back on it have told me that Leanne is a believable character. I worked hard to make her so. Research helps, talking to the right people is even more helpful, and of course the writer's imagination can help fill in the gaps.
"Write what you know" is good advice. But "know what you write about" is even better advice.