Dance very close to your partner; use smaller steps; don't whap people with big-kicking boleos. While we no longer settle collisions with a knife fight in the alley, bumping other people is not considered to be good form. Don't zig-zag across the lanes. At some of these festivals you see a few dancers zipping around really fast. Avoiding collisions, they think they are pretty hot, ignoring the wake of disruption they have created by all the near-misses.
(from argentine-tango.com (http://www.argentine-tango.com/dance/index.php?n=Main.TipsForDancing))