The general advice for any inexperienced author is to write about what they know. Which is okay if we know a lot but otherwise can be a challenge.

In my case, I've written a novel ("The Itch That Couldn't Be Scratched", available on Amazon and elsewhere from 1 March) that is loosely, very loosely, based on my own life and surroundings. Or at least it started that way and then diverged a lot. It had to because I don't lead the most interesting of lives.
I guess what all authors need to do is be observant of everything that happens around them. Take notes, record events and built up a store of experiences. Treat nothing as too trivial because you never know.