When I write, I think in terms of "scenes." When I shift the location or the point-of-view character, that's when I begin a new scene.
Scenes help me organize my stories, help me visualize them. I begin by orientating my readers. I write contemporary novels, so there's no magic happening, which requires authors to invent the physics of their worlds. So in a way, I've got it much easier than my paranormal and fantasy author colleagues. But in another way, I've got it harder because my worlds have to feel real.
That's an important concept -- feel real, not be real. And when the most popular piece of writing advice you get is "write what you know," that's tough to do unless you've been to a specific place. Let's be real (Ha!), first-hand research isn't always possible and when you're juggling a day job and family on top of writing, it's that much harder.
When I'm going for realism, I turn to Pinterest. I have boards for nearly all of my novels. There's a scene in SOME BOYS that takes place in one of the secondary characters' basement playrooms. I found a pin that depicted the basement I envisioned and "wrote to it." By this, I mean I kept that image on my screen while I conceived the scene. That helps me remember the details -- is the TV mounted on the wall or perched on a cabinet? Is the sectional sofa a left-hand or right-hand turn?
Seeing a space I'm going to use as a setting also helps me determine how my characters move within that space. Can my six-foot-tall hero cross that room in two paces or will it take him five?
Another technique I use is to try and find blog posts or Yelp reviews about the real places I find on Pinterest. This helps me add 'flavor.' But -- and this is a cautionary warning -- if I use a real place, I never show it in a negative way.
For example, three of my novels were based on my actual school district, but because they dealt with topics like bullying, school violence, sexual assault and victim-blaming, I fictionalized them because I didn't want the district believing I was casting dispersions. And because my local fire department never returned my calls when I was researching NOTHING LEFT TO BURN, I ended up basing my fictional Juniors program on that of three different fire departments.
In a still-unpublished story called THE SKY WAS SCARLET, the hero has just inherited his dad's '69 Pontiac GTO. It's a convertible. I couldn't find out online if the convertible ever had shoulder belts in that year. Shoulder belts were just coming out back then but in a convertible? I couldn't tell. I turned to Pinterest and found some car interior shots to use. Another thing that helped me is finding out how to raise and lower the top -- where was the switch located? Pinterest helped me answer these questions.
While not precisely world-building in the commonly understood sense, 'set design' for fiction is nevertheless an essential ingredient in the writing process. I hope this tip helps you design yours.