Dance floor etiquette

Join the back, not the front. If a dance has started, slot in at the back or edges rather than walking across the lines.
Know it before the middle. If you're still learning a dance, dance it at the back or side so people behind you aren't copying your mistakes.
Keep your line. Stay in line with the people beside you and leave space in front and behind.
Travelling dances move round the room. If the dance moves anticlockwise round the floor, keep moving with everyone — don't stop in the "fast lane".
Don't teach on the floor during a dance. Help a friend afterwards, not in the middle of a busy floor.
Floor splits. Sometimes the DJ plays a track that suits two dances. Half the floor does one, half the other — follow the instructor's call.
No drinks on the floor. Spills on a dance floor are dangerous.
Be welcoming. Everyone was new once. Say hello to the person on their own.