If you have to go—or if you're coming back—while an entertainer is working, don't cross the dance-floor in front of the artist. Wait until the number is over; or, if you can, circumnavigate—flank the performer.
While dancing, don't wave to a friend at a table. You may put someone's eye out.... If your shoelace opens, don't stop on the dance-floor to tie it—move off.
If you must take somebody's phone number, write it at your table, not while on the floor. (Don't take it at all if her brute is bigger than you.)
Do not show off on dance-floors. Even if you are as hep as Fred Astaire, the other customers do not want to see you. Besides, the bouncer is not sympathetic to amateur talent.