On foot
Take the same route twice
A familiar path gives you a useful way to notice change.
Choose an easy loop
Pick a route that is comfortable to repeat. A few streets, a courtyard or the edge of a park can be enough. The point is not distance but a small set of places you can recognise.
Look for one kind of detail
On the first walk, notice shadows. On the next, look for textures or the way people use a space. Changing the question can make a familiar place feel surprisingly new.
Keep the record modest
A sentence and a quick sketch will often preserve more than a large collection of photographs you never sort. Make a record you will actually want to look at again.