For the Gentleman: How Do I Ask a Lady to Dance?
The most appropriate way to ask a lady to dance is the use of
cabeceo. This is an art and is to be mastered.
It involves catching the attention of the lady you want to dance with by the way you are looking at her. If the lady wants to dance with you, she will acknowledge you by the way she looks at you. You will then nod towards the dance floor and she will indicate her consent by subtly nodding back. When that happens you walk towards her, extend your hand and guide her to the dance floor. There, you will enter the line of dance without disrupting its flow and begin dancing.
If the lady does not want to dance with you, she will simply look away when you try to catch her attention.
For the Lady: How Do I Accept or Decline an Invitation?
The elegant way to accept the invitation is by clearly yet subtly indicating your consent with eye contact and a slight nod after the initiator has nodded. Wait for the gentleman to come to you. Stand up only when he is in front of you and has extended his hand. If you stand up too early or too eagerly acknowledge him, you may find yourself in am embarrassing situation if he had in fact been communicating not with you but a lady sitting behind you.
To decline an invitation, simply look away.
Ladies do not invite but encourage invitations.
When Cabeceo is Not Used...
The
cabeceo is wonderful to use because it saves everyone the embarrassment of a misunderstood intent. It is highly recommended to learn and practise that art. In Buenos Aires, almost all invitations are rejected unless the
cabeceo is used.
In some communities where people know one another rather well, the
cabeceo may not be used. Gentlemen and ladies alike simple walk up to the other and ask for a dance. In this case, you may go with the flow and verbally accept or reject the invitation.
Some ladies may find it difficult to reject. The best way to do so is to simply say 'No, thank you', without providing any excuses. Alternatively, the Tango shoes may be removed to indicate that she is not dancing.
How About Couples?
Couples who arrive at a milonga will generally make it clear to the people around them if they are open to dancing with others or not.
It is proper for the couple to dance the first and last tandas together.
If a couple is open to dancing with others, the man may begin by inviting another lady, indicating to other dancers that the lady is open to invitations.
If a couple prefers to dance only with themselves, they will not demonstrate any
cabeceos, and neither will the man invite other ladies. That does not however mean that they are not open to socializing with others.
A willingness to socialize does not mean a willingness to dance.
A willingness to dance does not mean a willingness to dance with everyone.
What If I Can't Dance & Just Want to Watch?
That is perfectly fine. Simply look away when invited, or verbally reject. You are so welcomed to come and just enjoy the music and get to know other people...and perhaps attempt your first Tango-walk!