A side street is a good place to start

Choose a small boundary

Pick an area close enough to reach without turning the evening into a journey. A station, a bridge, and a public square make a useful triangle. You are looking for details within a manageable area, rather than trying to cover an entire city.

Give your attention a job

Look for one kind of detail: old shop lettering, doorways, pocket gardens, or the way people use a corner. A simple theme turns wandering into observation. Keep the phone in your pocket between notes so the walk has a chance to surprise you.

Finish somewhere familiar

Choose an easy return route and a place to pause before heading home. Note one street worth revisiting in different light. The reward is a new relationship with a place you already pass, rather than a distance recorded on a screen.