What is done and not done at a social?
Dance floor etiquette
The rules nobody writes down but everybody follows: how to say no, how not to collide, and what to do if something makes you uncomfortable.
Saying no
You can turn down any dance, at any time, without giving a reason. "Not right now, thanks" is enough and offends nobody.
And the other way round: if someone turns you down, accept it first time. Pushing is the one thing that is genuinely frowned upon.
One song, not three
The norm is one song per person. At the end you say thanks and both move on. Dancing three or four in a row happens, but you ask first.
If someone wants to leave halfway through a song, let them. They may have a thousand reasons and none of them are your business.
Not colliding
Whoever leads is responsible for watching where the couple is going. On a full floor that means smaller figures and fewer big turns.
If you bump into someone, you apologise and carry on. It happens constantly.
If something makes you uncomfortable
Stop the dance and walk off the floor. You do not have to finish the song out of politeness, and you owe nobody an explanation.
Almost every venue has someone from the organisation you can tell. If something serious happens, tell them: the socials that work are held together by exactly that.