As I've mentioned before, working a "real" job, especially in retail, is a great way to meet a lot of people and learn just enough about them to gather ideas for fictional characters (but not so much that your social life threatens to take over your writing time!)
I have two jobs, but I'll focus on only one--not the Walmart cake decorating job (I don't write horror so some of my character inspirations might not be suitable for all audiences... believe me, some people get crazy when you don't have the right Disney character cake design available for their child's fourth birthday!) Instead, I'll tell about how my part-time job--"vino-slinger" at Noisy Water Winery--helps me create some of my characters.
A writer needs to be a good listener if he or she wants to learn how to create distinct character voices and personalities. When you're behind the bar, you meet a lot of people and hear a lot of stories. And sometimes, once they have a few ounces of wine in them, you meet even MORE new people and hear even more stories.
Recently, my husband and I were sent by the winery to work at a wine festival in Santa Fe, New Mexico. Not only did we get to spend a lot of time with co-workers we don't normally see very often, but we learned a lot about them. They were all younger than we--okay, we were old enough to be their parents!--and I was able to see how a younger generation acts and speaks and interacts with other people.
Also, Santa Fe has a very different feel to it than our hometown does and that's reflected in the people there. Yes, some were snobs who didn't like ANYthing we poured for them, even if it had won medals from the state fair and the Fingerlakes International Wine Competition, and some were overly-enthused about everything they were served. But it was fascinating, for this writer, to watch strangers interact with each other--well-to-do retirees who only drink California wines; "grandmas gone wild" with their matching blouses and wide-brimmed sun hats; sunburned ranchers and farmers who know how much work goes into producing wines; young people sporting various body art and piercings and wildly-dyed hair whose IDs must be double-checked (they understand and never give trouble over it); and young families just out for a good time.
It would be so easy to stereotype them if one didn't have the opportunity to observe them interact. Soon Grandma in her pink-striped blouse with the cats on it is asking young Goth-looking guy if it hurt to have so many piercings put in and he graciously answers as they sip merlot. Sunburned rancher notes the Vietnam veteran hat on the retiree wearing a Ralph Lauren polo and soon they're exchanging stories over a sample of chardonnay. And Mom reaches over three kids' heads to give a reluctant Dad a sip of her riesling before he's pushing to the front and asking what else I've got to offer (even though he usually drinks beer, you know....)
True, I will retire to my "garret" (i.e. my dining room table) to write down the stories of the characters that were inspired by the people I met, but it's good to know that there will always be more characters out there, waiting for me to meet them. And maybe they'll like the wine, too!
That's me on the far right with the Noisy Water gang, toasting our new-found friends!