As were skirts, shorts, shirts made from the same cloth. Grubby jeans, old shorts anything goes. No need for anything because everyone has everything you can afford. If you have to take anything take something to eat for yourself in case host forgets about dinner. It might come in handy when you are starving and there is no sign of food.
People rang bells or knocked politely.
You look lovely' or something nice like that. Walk up to the door, push it open and enter. If doors are secured from inside, try windows and if windows are secured too then it is likely that your host has changed his mind about dinner. In such a case wait till something opens and enter. Small talk would begin, gifts would be given, lousy jokes exchanged and little groups were formed based on sex and age.