In my classes and workshops, I frequently sort people into groups. The key principle I use is to do random sorting. It helps to have a transparent system that makes it clear that the teams were determined strictly by chance. It prevents anyone from feeling left out, and it eliminates any suspicion of favoritism or manipulation of the groups. It also lands unusual combinations of people together — which is precisely the point.
To do this, I try to avoid the generic and overused “count off 1, 2, 3, 4, etc.” Instead, I used plastic silverware in multiple colors and had people sort by forks, knives, and spoons or by their color. I used playing cards and sorted by black/red, by suit, or by number. I’ve used coins — and groups are determined by which coin they received in a sealed envelope that they chose. I’ve used different kinds of fun-sized candies, and different stickers on the nametags that they chose to write their names.
When I need a last-minute sorting, I count off using categories (the Great Lakes, TV characters, Presidents, or food groups). You can also tie this impromptu sorting to a theme (e.g. we had mummies, monsters, black cats, and skeletons for a group on Halloween).
How you put people together matters. Don’t let people self-select and end up with those they already know. Foster connections and contributions by intentionally mixing people up in unexpected ways.