I think that a good exercise in Street-Photography is to take pictures of silhouettes & shadows. First of all: shadows are better at sundown or sunrise because they are longer that in other times of the day. The second tip is to go in the same place just at those times of day because the shadows are very different and the scenes can be better. In any case patience must be our preferred “weapon”: we can find a good mix between shadows and lights but we have to wait for the right subject! At the end: don’t forget to expose for the lights…better using spot-meter and locking the measure…so when your subject is coming we are ready for the snap.