What works for main streets?

As we research widely, and travel and observe, time and again we are reminded that a mix of the below is a universal recipe for successful main streets.

Gentle Density. Friendly Scale
Greening
Attractive Public Spaces
Pedestrian and Cyclist Friendliness
Mixed use
Interesting Urban Form

Jan Gehl, in particular, with his observations of pedestrian movement has lifted cities worldwide by making them both more amenable and more prosperous.