I shoot these primarily during cocktail hour.

I literally take *one* photo of each person, and one photo of a couple or groups of people.

One photo each and move on.

The key is to find a spot with great light near the cocktail hour area and then just walk up to people and asking to take their portrait. They say yes 99% of the time and I lead them to the nearby spot with good light and take a single photo.

There is more to this process as it is kinda complicated to crank out 30-50 portraits in an hour.

I will be going into this in depth at my workshop during the Musea Gathering in Nashville this February.

http://blog.mymusea.com/day/2012/06/27/