My advices especially for male dancers.
Sometimes some people go to milongas for just watching and they dont know how to dance. And you had better not to ask them for a dance because you will be rejected. So, how can you know if someone in a milonga knows how to dance or not? If you are a male, you can easly find out if a woman can dance or not by just looking at her shoes. If she doenst wear a high-heel shoe, she probably cant dance so keep away from her
You should be careful before asking for a dance from a woman who has just rejected a man. Because she might be a beginner or she doesnt know how to dance. And dont try to ask for a dance from a woman who rejects more than one men
When you are sitting in a milonga watch the dance floor and decide who you want to dance with.
Let the woman decide close or open embrace. Do not try to dance close embrace if the woman doesnt want.
Never go to milongas before taking a shower and use perfumes.
(Please add your own advices)