Three or four criteria are key, all seen on my current favourite Toronto residential street, Hilton Avenue, which runs south from St. Clair, one east of Bathurst. There's a distance of about 30 metres between the house fronts on one side of the street and the other. The houses are close to each other, with few spaces between them, and most are three stories high. These characteristics create a sense of enclosure so you know you're on a street, not walking through a field. Most houses have front porches, which provide a friendly transition between the public and private edge of the street.
People often sit there, or on the front steps, watching what's going on.
There are many large trees, providing lots of shade. The front yards are small. Large front yards defeat most households, and residents settle on boring, uninspired lawns. But small yards often encourage amateur green thumbs. Many houses are identified by their front yards.