Portraits of Strangers, photos by Danny Santos II. (The photos scroll to the right.) It's clear he's a very good DOM.
I wonder how the photographer manages to get such nice pictures while standing on the street. I mean, it's kind of tough to set the composition up ahead of time.
I think the two most important things when photographing people are the light, and the background. When you get serious about photographing, you train yourself to look for useful backgrounds, and to check each picture for the background before shooting (time permitting, of course).
Also, a very blurred background helps enormously. It's almost harder to make it look bad. Which is why I always recommend people-photographers to get lenses which can do this.