Like most authors, I've done (do) a ton of stuff to help support the writing. Luckily, a lot of it's been writing-related (editing, mentoring young authors). When I first got started writing, I was teaching private piano and guitar lessons. My interactions with young people actually inspired me to start writing YA!
My current side hustle mostly involves helping my brother, who runs an antiques and collectibles business. I spend quite a bit of time going on buying trips with him. I'm sure you're expecting me to tell you this gives me an opportunity to push myself away from the desk and refresh.
That's true--nothing like getting a chance to clear the head and rest for a moment. Helps you come back to your current WIP with better focus. But this hustle does much more than that.
For an antiquer, buying trips include estate sales. Lots of them. And for the most part (morbid as it sounds), most estate sales are conducted at the end of a life. The family takes the most important heirlooms. They hire a company to price up the rest. Sellers like my brother come in to scoop up bargains or vintage finds for clients--professional decorators, costume designers, etc.
But things--a whole lifetime of them--also tell stories. In the midst of the cleaning supplies and the clothes and the knickknacks, you begin to see who the person was. A seamstress. A musician. A world traveler. I've been in homes overflowing with original art collections. Homes with antique furniture. One home looked exactly like the inside of an old bar--pool table, neon liquor signs, etc.!
It's not just china dishes and half-emptied boxes of Miracle-Gro out in the garage. You can see what was important to that person. You know if they were religious. How close the family was. Sometimes how many children they had. Whether they were an animal person. If they were a vegetarian (cookbooks can tell a lot--trust me). You know how vain they were. What magazines they subscribed to. What they read, how they thought...
Sometimes, at the end of walking through a home, you can imagine the person who lived there, sitting on the bottom step of the basement stairs.
You see lives--and that begins to help you shape characters. You give your characters the kind of furniture--the cook books, the knickknacks, the clothing, etc.--that helps your readers get to know them.
The things we choose to surround ourselves with tell our story. They can help your characters tell their story, too.