As some others have mentioned, it really depends on what the town is for, how big it is, and what the PCs' relationship to the town is - and of course, how developed the details of the town might be.
When possible I like to give the PCs a map of the town (establishing this conceit in whichever way makes the most sense: they have a guide, one or more have been here before, someone gave them a map, the entrance to the town gives a good view of its layout from above) with one or two prominent features numbered and then numbering more as we go through and the PCs explore. Once a place is numbered, the players can say, I make my way to #13 - the Snapping Line, or whatever.
Of course, small villages or just passing through doesn't need that detail, and assuming minimal threats we can cover the downtime with a "to-do" list (either individually or as a group or some combo) that I go down and adjudicate what on the list can be just considered done, costs money, or requires a scene.
I usually take maps from adventures or online sources and then modify them in photoshop. For example, Saltmarsh, which is where both my current campaigns are set, looks like this in my game:
You might notice that some of the numbers are all over the place, that is because discoveries or events have added numbered spots. Thus the refugee camp and temporary militia encampment at #33 was added after a local threat started attacking local fishing villages and people fled to a bigger town to safety. #32 is the party's lodge and the property line for it.